Cesaro made his WWE television debut on the April 20, 2012, episode of SmackDown, appearing in a backstage segment with Aksana and Theodore Long, ending with him going to talk to General Manager John Laurinaitis about a contract. In storyline, the multilingual Cesaro served in the Swiss militia, before embarking on a career in rugby, which ended with him being banned for "excessive aggression". The following week, Cesaro defeated Tyson Kidd in what was billed as a tryout match. In May, Aksana revealed that she and Cesaro were lovers. On the July 3 Great American Bash SmackDown, Cesaro suffered his first loss, when he and Aksana were defeated in a mixed tag team match by The Great Khali and Layla, though Cesaro himself was not pinned. On the July 27 and August 3 episodes of SmackDown, Cesaro scored back-to-back non-title wins over United States Champion Santino Marella. On the following SmackDown, Cesaro suffered his first loss in a singles match as he was pinned by Christian. On August 19, during the SummerSlam pre-show, Cesaro defeated Santino Marella to win the United States Championship, his first title in WWE. Cesaro made his first televised title defense on the September 3 Raw, defeating Marella in a rematch. Cesaro next defended the title from Zack Ryder on September 16 at Night of Champions. On the September 21 SmackDown, Cesaro ended his relationship with Aksana, after an inadvertent distraction from her cost him his non-title match with Santino Marella. This led to a title rematch between Cesaro and Marella the following week, where Cesaro was able to retain his title.
After Cesaro was defeated by Justin Gabriel in a non-title match on the October 22 Raw, the two were booked in a United States Championship match six days later at Hell in a Cell, where Cesaro successfully defended his title. Cesaro then began feuding with R-Truth after Truth saved Kofi Kingston from a post-match assault from Cesaro on the October 29 Raw. At the same time as his feud with Truth, Cesaro successfully defended his title against Tyson Kidd on the October 31 episode of NXT. On November 18 at Survivor Series, Cesaro defeated R-Truth to retain the United States Championship. The feud continued on the following SmackDown, with Truth defeating Cesaro in a non-title match. Cesaro then defeated Truth in two more matches, first in a four-way match, which also included Kofi Kingston and Wade Barrett on the December 3 Raw and second on December 16 at TLC: Tables, Ladders & Chairs in a singles match, to retain his title. On the December 31 Raw, Cesaro issued a title challenge to Sgt. Slaughter as part of the "Champion's Choice Night" and then defeated Slaughter in the match that followed to retain his championship. Two days later on the January 2, 2013, episode of WWE Main Event, Cesaro defeated The Great Khali to retain his United States Championship. Afterwards, Cesaro began a feud with The Miz, who confronted Cesaro after he insulted Americans as being soft. In the pre-show of the Royal Rumble on January 27, Cesaro defeated Miz to retain the United States Championship. Later on in the pay-per-view, Cesaro entered his first Royal Rumble match at number twenty-two, but was the eighteenth man eliminated by the eventual winner John Cena. Cesaro's feud with Miz continued on February 17 at Elimination Chamber, where he retained the United States Championship via disqualification after Miz accidentally hit him in the groin. Cesaro and Miz faced off in Two-out-of-Three falls match for the United States Championship on the March 1 SmackDown, where Cesaro again retained his title. During the March 21 NXT tapings which aired on April 24 due to tape delay), Cesaro successfully retained his title against Adrian Neville during the "Clash of the Champions" NXT. On the April 15 Raw, Cesaro lost the United States Championship to Kofi Kingston, ending his reign at 240 days. Cesaro received his rematch for the title on the May 1 Main Event, but was again defeated by Kingston.
On NXT, Cesaro started a feud with Sami Zayn on May 22 NXT, where Zayn scored an upset over Cesaro in his debut match. Cesaro later defeated Zayn in a rematch. On the 17 June Raw, Cesaro was revealed as the new associate of Zeb Colter and defeated William Regal. Cesaro began agreeing with Zeb Colter's views on America, much to the dismay of Michael Cole because Colter's xenophobic disposition ended up with a foreign-born patriot as a new disciple, while Cesaro's Eurocentrism goes against his anti-America views. On the July 3 NXT, Cesaro unsuccessfully challenged Bo Dallas for the NXT Championship. On July 14 at the Money in the Bank pay-per-view, Cesaro and Colter's fellow client Jack Swagger competed in the World Heavyweight Championship Money in the Bank ladder match, but were both unsuccessful as the match was won by Damien Sandow. The following night on Raw, Cesaro and Swagger, now billed as "The Real Americans", teamed together for the first time, but ended up being defeated by The Usos. On July 17 NXT, Cesaro was defeated by Leo Kruger in a triple threat number one contenders match for the NXT Championship, which also included Sami Zayn. On the August 21 NXT, Cesaro defeated Zayn in a two-out-of-three falls match to conclude the feud.
On September 15, during the Night of Champions pre-show, the Real Americans competed in a number one contender Tag Team Turmoil Match for the WWE Tag Team Championship, in which they were the last team eliminated by The Prime Time Players (Darren Young and Titus O'Neil). Simultaneously, the Real Americans began a feud with the returning Santino Marella after he defeated both of them in singles competition. On October 6 at WWE Battleground, the Real Americans defeated Marella and The Great Khali in a tag team match. The Real Americans moved onto feuding with Los Matadores, culminating in a tag team match on October 27 at Hell in a Cell, which Los Matadores won. The following night on Raw, The Real Americans defeated WWE Tag Team Champions Cody Rhodes and Goldust in a non-title match.
In the beginning of 2014, The Real Americans competed against several tag teams (Rey Mysterio and The Big Show/Sin Cara as well as The Usos), but weren't successful in winning. Cesaro and Swagger also competed in the 30-man 2014 Royal Rumble match at the Royal Rumble, entering at number 21, but were both unsuccessful as Cesaro was eliminated by Roman Reigns. On the January 31, 2014 episode of SmackDown, Cesaro defeated Dolph Ziggler to earn a spot in the Elimination Chamber match for the WWE World Heavyweight Championship. On the February 14, 2014 episode of SmackDown, Cesaro was billed just simply as "Cesaro", and defeated the WWE World Heavyweight Champion Randy Orton in a non-title match. At the Elimination Chamber, Cesaro was the third participant eliminated by John Cena after he submitted to the STF. On an episode of Smackdown, The Real Americans were arguing, yet they still won the match when Cesaro neutralized Mark Henry. At the WWE Network event NXT Arrival, Cesaro defeated Sami Zayn for a fourth time. Afterward the two embraced and Cesaro showed respect for Zayn. Also, Cesaro's partnership with Swagger began to show cracks, with the two regularly getting involved in each other's matches, causing the other to lose by disqualification and almost get pushy with each other as a result. However, the team have held it together to go be a part of WrestleMania XXX in a turmoil match.
The Real American's took part in the Wrestlemania Pre Show in a fatal four way involving Los Matadores, Curtis Axel and Ryback and The Usos. Cesaro and Swagger were the last team to be eliminated. After the match Swagger yelled at Cesaro for inadvertently knocking him from the ring, leading to an attempted Patriot Lock on Cesaro before Zeb ordered him to shake Cesaro's hand. Cesaro tricked Swagger into thinking the two would reconcile, before turning face and giving Swagger the Cesaro Swing, putting an end to the Real Americans.
Cesaro was announced as a surprise entrant in the Andre the Giant Memorial Battle Royal at WrestleMania XXX, which he won by last eliminating The Big Show mirroring Hulk Hogan's victory against Andre via body slam. After the match Cesaro shook Big Show's hand as a sign of respect thus officially turning face for the first time in his WWE career.
On the post-WrestleMania Raw, Cesaro's victory was endorsed by Hogan. Cesaro proceeded to dump Colter as his manager, instead revealing that he was a new client of Paul Heyman. Cesaro would compete in the Intercontinental Championship Tournament to determine the number one contender for the championship at Extreme Rules, beating Mark Henry in the quarter-finals, but losing to Rob Van Dam via countout in the semifinals due to interference from Swagger and Colter. This led to a triple threat match at Extreme Rules against Van Dam and Swagger, which Cesaro won. Cesaro then fought United States Champion Sheamus to a double countout on the May 13 episode of Main Event. On the May 19 episode of Raw, Cesaro defeated Sheamus in a non-title rematch due to some slight interference from Heyman, setting up the title match at Payback, which Sheamus won, ending Cesaro's winning streak since joining Heyman. On June 9th, Cesaro defeated Rob Van Dam to qualify for the Money in the Bank ladder match for the vacant WWE World Heavyweight Championship. This match was won by John Cena. Cesaro then started feuding with Kofi Kingston. Cesaro would lose matches against Kingston on June 30th and July 7th editions of Raw, in which Cesaro would attack Kofi after each match. On July 11th edition of Raw Cesaro faced Big E. During the match, Kofi came out and distracted Cesaro, which allowed Big E to pick up the victory. At Battleground, Cesaro eliminated both Big E and Kingston in an Intercontinental Championship battle royal, but was surprisingly eliminated by Heath Slater. The next night on Raw, Cesaro announced he was no longer a "Paul Heyman Guy", and wanted to become a "Triple H Guy". On the July 28 episode of Raw Cesaro lost to WWE World Heavyweight Champion John Cena, and on the August 2 episode of SmackDown, Cesaro would lose to former tag team partner, Jack Swagger. At SummerSlam, Cesaro was defeated by Rob Van Dam in a pre-show match. On the August 25 episode of Raw, Cesaro defeated Rob Van Dam to become the number one contender for Sheamus' WWE United States Championship at Night of Champions. However, he was unsuccessful in capturing the title. Cesaro won a battle royal on the September 26 episode of SmackDown to determine the number one contender to Dolph Ziggler's Interncontinental Championship, however he was unsuccessful in capturing the title later that night. He also failed to capture the title in a two out of three falls match at Hell in a Cell, losing two consecutive falls, and again on the November 14 SmackDown after being eliminated first by Tyson Kidd in a triple threat elimination match. On the November 17 episode of Raw, Cesaro teased a face turn as he appeared to be the final member of Cena's team, but it was a ruse as he turned back to join Team Authority against Team Cena at Survivor Series, remaining a heel.
In late 2014, Cesaro and Tyson Kidd teamed to try and become the #1 contenders for the WWE Tag Team Championships, but were unsuccessful in doing so. Shortly after, on the December 18th episode of Superstars, the duo successfully defeated Los Matadores, and debuted a new double team finishing move. On the December 29th episode of Raw, Cesaro was defeated by the returning Bad News Barrett. The duo of Cesaro and Kidd yet again defeated Los Matadores on the January 2, 2015 episode of SmackDown!, and were given their own entrance video using footage of both men, and Cesaro's music. On the January 5, 2015, episode of Raw, Cesaro and Kidd would pose as members of Adam Rose's rosebuds, attacking The New Day during Rose's match with Big E. On the Royal Rumble pre-show, Cesaro and Kidd defeated The New Day. Later that night, Cesaro entered the Rumble match at number 28, however he was eliminated by Dolph Ziggler. At WWE Fastlane on February 22, Cesaro and Kidd defeated The Usos to capture the WWE Tag Team Championships. They retained their titles in a rematch the following night on Raw after Natalya caused a disqualification. Cesaro and Kidd managed to retain their titles at WrestleMania 31 in a match that included three other teams. Cesaro also competed in the memorial battle royal, but was thrown out by Big Show who he had actually eliminated the prior year. At Extreme Rules, Cesaro and Kidd lost the Tag Team Championships to The New Day (Big E and Kofi Kingston), ending their reign at 63 days. He and Tyson Kidd turned face after receiving a positive crowd reaction. They failed to regain the championships on the April 30 episode of SmackDown, and at Payback in a 2-out-of-3 falls match, with Xavier Woods interfering in both matches. At Elimination Chamber, Cesaro and Kidd competed in the first ever tag team Elimination Chamber match, but failed to win the titles.
On the following Raw, Tyson Kidd was injured while facing Samoa Joe in a dark match, and needed surgery for a neck injury. Following that, Cesaro began to compete alone on Superstars and Main Event, defeating the likes of Bo Dallas and Luke Harper. On June 18, episode of SmackDown, he returned to television when he went up against Kevin Owens but subsequently lost the match. On the June 29 episode of Raw, Cesaro answered John Cena's United States Championship open challenge and won by disqualification after Kevin Owens interfered. He faced Cena for the championship again on the July 6 episode of Raw, losing by pinfall. On the July 13 episode of Raw, Cesaro confronted Kevin Owens and Rusev about who should have face Cena for the championship. This resulted in a triple threat match, where the winner would face Cena immediately after, which Rusev won. On the July 16 episode of SmackDown, Cesaro became only the second man (after Cena) to pin Rusev in a singles match. In the main event of the July 20 episode of Raw, Cesaro teamed with John Cena and Randy Orton to defeat Sheamus, Kevin Owens, and Rusev. He would then enter into a feud with Owens when Owens attacked Cesaro after Cesaro lost to Seth Rollins on the July 23rd 2015 edition of SmackDown. Cesaro teamed up with Randy Orton to defeat Sheamus and Kevin Owens on the August 17 episode of Raw. It was then announced that Cesaro would face Owens at SummerSlam, where Cesaro would ultimately lose the match. In a SummerSlam rematch on the August 31, 2015 Raw, Cesaro was again defeated by Owens after bruising his ribs on the announce table. In the subsequent weeks Cesaro's importance was downplayed, being used instead to further feuds he had no part of. On the September 7 episode of Raw, Cesaro faced The Miz and the match was declared a double count-out. After the match, Cesaro was knocked out by Big Show. Cesaro started appearing on Superstars and Main Event defeating the likes of Heath Slater, Bo Dallas and Adam Rose on the following shows. At Hell in a Cell in October, Cesaro teamed with Neville and Dolph Ziggler to defeated Sheamus, Rusev, and King Barrett on the Kickoff show. Cesaro defeated Sheamus on the November 9 episode of Raw to advance to the quarterfinals in a tournament to crown a new WWE World Heavyweight Championship at Survivor Series after previous champion Seth Rollins injured his knee at a house show in Dublin. The next week on the November 16 Raw, Cesaro lost in the semi-finals to Roman Reigns. On November 23, WWE announced Cesaro had torn his left shoulder rotator cuff two months before and needed surgery immediately, leaving him out of action for 4 to 6 months.
Cesaro made his return from injury at the April 4, 2016 episode of Raw, where he replaced Sami Zayn in the fatal 4-way match between himself, Kevin Owens, AJ Styles and Chris Jericho to determine the #1 contender for the WWE World Heavyweight Championship, but the match was won by Styles. He then teamed with Styles to defeat Owens and Jericho in a tag team match on the following SmackDown. On the April 11, 2016 edition of Raw, Cesaro defeated Kevin Owens to become the #1 contender for the WWE Intercontinental Championship. The match between him and reigning champion The Miz was then scheduled for WWE Payback. At Payback, Cesaro was defeated by The Miz after interference from Owens and Sami Zayn. A Fatal 4-Way Intercontinental Championship match between Cesaro, Miz, Owens, and Zayn was then made for the Extreme Rules pay-per-view on May 22, where the Miz prevailed once again. The following night on Raw Cesaro again faced Miz, this time for a spot in the Money in the Bank ladder match on June 19 for a chance at a guaranteed contract for a WWE World Heavyweight Championship match, with Cesaro winning the place in the ladder match by pinning The Miz after a Neutralizer; this consequently also earned Cesaro another Intercontinental Title match, which was held on that week's Smackdown and where The Miz again pinned Cesaro to retain the belt. On the June 6 episode of Raw, Cesaro defeated fellow Money in the Bank match competitor Chris Jericho via submission with the Sharpshooter. At Money in the Bank, Cesaro was unsuccessful in winning the match as it was won by Dean Ambrose.
On the July 19 episode of SmackDown, Cesaro took part in the 2016 WWE draft and he was drafted to Raw in the 6th round. After the draft, Cesaro started a feud with Sheamus. He defeated Sheamus in two consecutive matches, resulting in Cesaro earning a championship match for the WWE United States Championship. On the August 8 episode of Raw, Cesaro was given an impromptu United States title match against Rusev, which he lost following a distraction from Sheamus. The next on Raw, Cesaro cost Sheamus his match against Sami Zayn. Mick Foley then announced that the pair will face each other in a best of seven series match with the first match taking place at SummerSlam, in which he was defeated. Sheamus would defeat Cesaro in the second and third matches, but Cesaro would defeat Sheamus in the fourth and fifth matches. At Clash of Champions, Cesaro fought Sheamus to a no contest when neither man could continue, leaving the outcome of their best-of-7 series in question. On the next night's Raw, RAW General Manager Mick Foley approached both Cesaro and Sheamus backstage, telling them that they both impressed during their series, and that they were both guaranteed a WWE Tag Team Championship match as a tag team. Later that night, the team defeated two local competitors while trying to out-do each other. Both Cesaro and Sheamus defeated The New Day on the October 24 episode of Raw but were unsuccessful winning the championships at Hell in a Cell. On the November 7 episode of Raw, Cesaro and Sheamus were announced as part of Team Raw for the 10–on–10 Survivor Series Tag Team Elimination match at Survivor Series on November 20, 2016, which Team Raw won with Cesaro and Sheamus being the sole survivors for their team. The next night on Raw, Sheamus and Cesaro again failed to capture the tag titles from New Day. They received another title shot at Roadblock: End of the Line, where Cesaro and Sheamus were finally able to defeat The New Day to win the Raw Tag Team Championship, marking Cesaro's second reign.