The Black Cats have agreed a four-year deal for the combative 21 year-old, who will link up with former Latics boss Steve Bruce at the Stadium of Light.
Cattermole will go straight into the squad for Sunderland's Barclays Premier League opener against Bolton on Saturday.
The former Middlesbrough youth team player, signed by Bruce for Wigan in a £3.5million deal in July 2008, becomes Sunderland's fifth signing of the summer after Darren Bent, Lorik Cana, Fraizer Campbell and Paulo Da Silva.
Cattermole made 69 first-team appearances for Middlesbrough and featured in 33 Premier League games in his lone season at Wigan.
Latics manager Roberto Martinez admitted his disappointment at losing the services of the England Under-21 international.
"The fee is a good one," said Martinez. "It is far more than the club paid for him last year and the third highest in Wigan Athletic history.
"The initial offer from Sunderland was unacceptable as we said at the time, but they have now matched our valuation.
"The speculation about Lee has refused to go away over the last few weeks and this has been very unsettling for him and for our players.
"It became clear over the past days having spoken to Lee that he wanted to leave and it is very disruptive to the group when a player is clearly unhappy.
"My No 1 priority has to be the good of the club and it left me with a decision to make, I therefore agreed to the move for the good of the players we have at the club and who want to remain with us and help us progress to the next level."