After briefly working on the independent circuit and in Extreme Championship Wrestling, she signed with the World Wrestling Federation in 1999. Originally, she was paired with Essa Rios, but she achieved her greatest push alongside Matt and Jeff Hardy as Team Xtreme.
Dumas had an off-screen relationship with Matt Hardy, which ended in 2005 after her affair with Adam "Edge" Copeland. WWE used the real-life drama between the trio as a storyline throughout 2005 and 2006, which led to Dumas being booed by the fans for the first time and her character becoming more villainous on-screen.
Lita faced Trish Stratus at Unforgiven, in which Lita dropped the Women's Championship to Stratus in what was Stratus' last WWE match. On the November 20 edition of Raw, after defeating Mickie James in a non-title match, Lita announced that she would be retiring from WWE after her match with James at Survivor Series.
Because of the off-screen issues with Matt Hardy, fans began to shout obscenities to her during her matches. By November, Dumas had decided to let her contract expire and retire. At Survivor Series, on November 26, 2006, Lita was pinned by Mickie James, losing the Women's Championship in her final match in WWE. The day after her retirement, Lita stated that her plans to retire began around mid-2005, when the feud between Edge and Matt Hardy was at its height. Because of her involvement in the feud, the harassment she received from some fans was so strong that she felt as if "even when she was walking the dog there was going to be someone yelling 'You screwed Matt!' out the window." Eventually, she became so fed up with the treatment she was receiving from these fans, she decided that the only way to avoid such harassment was to retire altogether.
Also unlike some of the "divas" on the current roster, Lita worked her ass off to achieve what she did.