Cena started his wrestling career in 2000 in the UPW as The Prototype. He then signed with the WWE, where they placed him in the OVW, the WWE's development circuit. Once on the WWE, his persona was a Vanilla Ice type white rapper. Note very appealing to the fans of the WWE, he slowly caught on with his biting rhymes and Word life moniker. He was teamed up with a couple of very forgettable partners that never went anywhere. In 2003, he started a feud with Brock Lesnar, developed his signature move the FU and the "you can't see me" schtick. He was unsuccesful against Lesnar but gained popularity. In 2004, he was eliminated in the Royal Rumble by The Big Show, starting a feud between them. He beat Show for the WWE United States Championship in Wrestlemania XX. He was then stripped of the title when the WWE made Kurt Angle the commissioner.

Still in 2004, he won the title back from Booker T. but for some strange reason he lost it the next week to Carlito Carribean Cool's debut in the WWE. In 2005, Cena pinned Angle to be the #1 contender for the WWE championship. On April 3rd, he beat JBL for the WWE Heavyweight Championship. In Novembers Survivor Series, Cena pinned Angle to retain the title. He then was forced to defend the title the next night in a fatal 3 way aginst Angle and Chris Masters. He made Masters tap out with his STFU to retain the title once more.

Cena kicked off 2006 by succesfully defending his title at New Year Resolution. BUT Vince McMahon came out after the match and said Edge was cashing in his money in the bank card to challenge Cena right then. He was easy picking for Edge and Edge took the title. Three weeks, to the day, after losing the title Cena defeated Edge at the Royal Rumble to regain the WWE Championship. He then succesfully defended the title against Triple H in Wrestlemania XXII.

In May 2006, Cena would lose the title again to RVD when Edge interfered and speared Cena twice. Allowing RVD to give him the splash and take the title. When Edge won the title from Van Dam in a Triple Threat match (also involving Cena) it re-ignited the feud between Edge and Cena. The opening stages of the feud saw Edge taking constant shortcuts in order to keep his title (losing by disqualification) while still seemingly getting positive reactions from most crowds. This lead to a Cena and Edge match at Summerslam, where Edge used brass knuckles twice to retain the title. It was at this time Cena started using militery moves and mannerisms to change his image and promote his new movie The Marine. Cena would then beat Edge for the title in a tables, ladders and chairs match on RAW.

The feud in 2007 is with Umaga. This is the dude from WCW called 3 minute warning, Rosie and Jamal(Umaga). He recently defeated Umaga to retain thethe WWE Heavyweight Championship. He also teamed with HBK to defeat Randy Orton and Edge for the WWE Tag Team Championship. During a match with Mr. Kennedy later in 2007 on Raw, Cena suffered a vivious injury, tearing a pec while doing a hip toss. Though he finished the match and took part in the scripted attack by Randy Orton after the match, surgery the following day found that his pectoralis major muscle was torn completely from the bone, estimated at the time to require seven months to a year of rehabilitation. As a result, he was stripped of the title in an announcement by Vince McMahon on the next night's episode of ECW. Thus ending what was the longest WWE Championship reign in over 19 years.

Cena made an unannounced return to action on January 27, 2008 as the final participant of the Royal Rumble. He won the match, and the traditional WrestleMania title shot, by last eliminating Triple H. Instead of waiting until WrestleMania, the title shot was cashed in against WWE Champion Randy Orton No Way Out. He lost by DQ.