The academy product has moved to Hillsborough for an undisclosed fee according to the club, although reports from the Yorkshire Evening Post claim the defender has moved for free.
Lees' move to the south Yorkshire outfit was all but confirmed on Wednesday night after he was pictured watching the club during their pre-season friendly against Newcastle United.
Owls boss Stuart Gray confirmed he was to have his medical on Thursday, and now Lees is no longer a United player.
While most are overjoyed at the news due to his poor performances, the move is sad in a way. Lees seemed to have plenty of potential and a number of bad performances seemed to ruin his confidence.
Leeds can't afford to keep players who don't make the grade unfortunately but it is always nice to see an academy product flourish in the first-team.
With less pressure on his shoulders, Lees may be able to improve his form for Wednesday in the next few years.
Head coach Dave Hockaday now has Jason Pearce and Scott Wootton as his centre-back pairing, meaning the club may need to bring in another option as either back-up or first choice.
It could be a very busy few days for United with other deals still to be completed.