In March 2001, Robinson was hired by the WWF. He debuted in the WWF as a member of The Alliance, bickering with WWF loyalist referee Jack Doan and accompanying senior WCW official Nick Patrick to ringside for his match at WWF Invasion on July 22, 2001. He refereed his first WWF match on July 2, 2001. Despite being a member of the Alliance, Robinson, unlike fellow Alliance member Nick Patrick, was mostly a fair and impartial referee. An example of this would be the August 20, 2001 episode of Raw when he awarded Tajiri a victory over Booker T by disqualification when Booker T started choking Tajiri with his shirt. The night before at SummerSlam, Robinson refereed Booker T's match against the Rock and called the match right down the middle as the Rock won the "Big Gold Belt".
In 2002, the WWF was renamed "World Wrestling Entertainment", and the roster was divided between two "brands", Raw and SmackDown!. Robinson was initially assigned to Raw, but was later traded to SmackDown!, where he refereed many women's matches. On the July 1, 2004, episode of SmackDown!, Robinson was forced to wrestle Luther Reigns by General Manager Kurt Angle. The match, however, was quickly stopped by Charlie Haas. In 2005, Robinson called the final match of WWE Hall of Famer Eddie Guerrero against Ken Kennedy on an episode of Friday Night Smackdown. Guerrero died 2 days after the match aired.
At No Mercy 2006, Robinson, who had refereed a match between Mr. Kennedy and The Undertaker, was on the receiving end of a Tombstone Piledriver from the Undertaker after he had called for him to be disqualified after hitting Mr. Kennedy with his WWE United States Championship belt. Robinson also officiated the World Heavyweight Championship matches at WrestleMania 22, WrestleMania 23, as well as Ric Flair's final match and the last part of the World Heavyweight Championship match at WrestleMania XXIV.
On the June 21, 2008, episode of SmackDown, Robinson was placed in a match by General Manager Vickie Guerrero after ejecting Chavo Guerrero from ringside during Bam Neely's match with Matt Hardy. He lost to The Great Khali in a squash match. After the match he was carried out by medical officials. He returned in a match between Edge and The Big Show, where he stopped Big Show from giving a con-chair-to to Edge. In November 2008 referees were made no longer exclusive to certain brands.
Charles also refereed Shawn Michaels retirement match at WrestleMania XXVI.
Charles Robinson was not present among the referees on the October 4, 2011 episode of RAW, when the entire WWE on air talent came to the ring and left in a unanimous (kayfabe) walk-out.
He is featured in the newest WWE video game WWE '12 as the referee.
At WrestleMania XXVIII, Charles was chokeslammed by The Undertaker for not making the count on Triple H. Robinson also refereed the WrestleMania 31 pay-per-view match which saw Triple H's successful victory against Sting. This was Sting's first ever match in WWE, and Sting personally chose Robinson as the referee. Robinson also refereed the match between Brock Lesnar and The Undertaker at SummerSlam 2015 where the match ended in controversy after Undertaker tapped out to Lesnar, but Robinson didn't see it but the timekeeper saw it and rang the bell. Undertaker then hit Lesnar with a low blow and made Lesnar pass out to the Hell's Gate. In a interview after the match, Robinson admitted that after watching the replays, Undertaker did tap out, but also confirmed that it didn't mattered if the timekeeper or the crowd saw it, and as long as Robinson didn't called for the bell, the match would continue. At Payback on May 1, 2016, he refereed the match between Charlotte (with her father Ric Flair) and Natalya (with Bret Hart) for the WWE Women's Championship. During the match, Robinson turned heel by calling for the bell when Charlotte had Natalya in the sharpshooter despite Natalya not submitting. This was similar to the Montreal Screwjob of Survivor Series 1997, when Bret Hart lost the WWF Championship.