Wells was selected with the number two overall pick in the 2002 AFL Draft and made his debut in 2003 playing 18 games and averaging 12 disposals per game. He rose to prominence in 2004 when, against Fremantle, he kicked the AFL Goal of the Year, jumping and taking the ball from ruck contest in the goal square and kicking the goal before he landed.
Wells was selected in the Australian team for the 2005 International Rules Series but was unable to play due to injury. He enjoyed a fairly good year in 2006 in which he averaged 18 disposals and finished 2nd in the Syd Barker Medal.
In 2008, Wells enjoyed a good season averaging 21 disposals and having a big impact in matches in the second half of the season during North Melbourne's winning period. He was rewarded with selection in the Australian side that lost to Ireland in that year's International Rules Series.
2009 was a disappointing year for Wells when injuries restricted him to just 7 games.
In 2011 Wells produced a brilliant and consistent season when he won his first Syd Barker Medal which he shared with Andrew Swallow. He would also be named in the 40 man All Australian squad but would miss out on being part of the final 22.
At the end of the 2011 season Wells had shoulder surgery during which it was discovered that he had a large blood clot on his lungs. While it is no longer a serious threat to his health and life it is still expected to be a major setback to his 2012 campaign.
In 2007, Wells appeared in a television advertisement for AFL on the Gold Coast and in 2009 and he featured in the official advertisement for the AFL, playing Australian Rules on an Association Football ground.