He made his television debut as "DH Smith" on the October 22, 2007 episode of Raw, defeating Carlito using his father's trademark running powerslam. He dedicated the match to his father, The British Bulldog. On October 29, Smith and Jeff Hardy defeated Carlito and Mr. Kennedy.
On November 2, 2007, it was reported that Smith had been suspended for 30 days due to violations of "WWE's Substance Abuse and Drug Testing Policy". Smith returned to the active roster on December 17 by defeating Charlie Haas on Heat. After his return, Smith would wrestle primarily on Heat.
On April 15, 2009, Smith was drafted to the ECW brand as part of the 2009 Supplemental Draft, without making any appearances on SmackDown. Smith made his ECW debut on May 12, as a villain, attacking Finlay during Finlay's match with Tyson Kidd, using the name David Hart Smith. Smith, Kidd and Natalya formed a new version of The Hart Foundation, named The Hart Trilogy at first, although on the May 27 episode of ECW, the name was tweaked to The Hart Dynasty. Smith was victorious in his first match for ECW, defeating Finlay on the May 19 episode, with help from Kidd and Natalya.
On June 29, The Hart Dynasty were traded to the SmackDown brand, and entered a feud with Cryme Tyme. At the WWE Bragging Rights pay-per-view in October, Smith and Kidd competed in a seven-on-seven tag match with Chris Jericho, Kane, Finlay, Matt Hardy and R-Truth as Team SmackDown to defeat Team Raw. In December 2009, they challenged D-Generation X for the Unified WWE Tag Team Championship, but were unsuccessful.
The Hart Dynasty appeared at WrestleMania XXVI, helping Bret Hart during his match against Vince McMahon, and the following night on Raw they defeated the Unified WWE Tag Team Champions ShoMiz (The Big Show and The Miz) in a non-title match at Hart's behest, effectively turning face in the process. At the Extreme Rules pay-per-view, Smith and Kidd earned a Unified Tag Team Championship match by defeating ShoMiz in a tag team gauntlet match (which also included the team of John Morrison and R-Truth and the team of Montel Vontavious Porter and Mark Henry). During the 2010 WWE Draft on the April 26 episode of Raw, The Hart Dynasty, accompanied by Natalya and Hart, defeated ShoMiz to win the Unified Tag Team Championship, when Kidd made The Miz submit to the Sharpshooter.
The following day, all three members of The Hart Dynasty were moved to the Raw brand as part of the Supplemental Draft. On the May 10 episode of Raw, he was defeated by Chris Jericho, granting Jericho and The Miz a shot for the Unified WWE Tag Team Championship at Over the Limit, but The Hart Dynasty were able to retain. The following night, on May 24, they were attacked by The Usos (Jimmy and Jey) and Tamina, provoking a feud. At Fatal 4-Way, The Hart Dynasty defeated The Usos and Tamina in a six-person mixed tag team match when Natalya pinned Tamina, and Smith and Kidd defeated The Usos at Money in the Bank to retain the championships when Smith made Jimmy Uso submit to the Sharpshooter. At Night of Champions, The Hart Dynasty lost the WWE Tag Team Championship to Cody Rhodes and Drew McIntyre in a Tag Team Turmoil match which also involved The Usos, Vladimir Kozlov and Santino Marella, and the team of Evan Bourne and Mark Henry.
After a failed attempt to regain the championship, in which Kidd was pushed off balance during their double-team Hart Attack move, Kidd and Smith began to have a falling out with one another. This culminated on the November 15 episode of Raw, when Kidd refused to tag in and attacked Smith during a match for the WWE Tag Team Championship against The Nexus (Justin Gabriel and Heath Slater). ending their partnership. On the December 2 episode of WWE Superstars, Smith beat Kidd in a singles match. Afterward, Smith offered to shake Kidd's hand, but Kidd slapped him across the face. On the next episode of Raw, Kidd defeated Smith in a rematch.
After losing to Kidd, Smith would be restricted to appearing on Superstars, mostly participating in tag team matches with Yoshi Tatsu or Darren Young. Smith's last match was on the April 28 edition of Superstars, where he lost to Zack Ryder. After months of inactivity, Smith was released from his contract with WWE on August 5, 2011. The following week on Raw CM Punk mentioned Smith being released from WWE.