Leeds have been heavily linked with the 22-year-old in recent weeks as manager Brian McDermott looks to add some creativity to a side dumped out of the FA Cup at League Two Rochdale last weekend and winless in their last five games.
Stewart has now made the move to Hull's Yorkshire rivals on a 93-day loan and agreed a three-year deal that will start in the close-season.
The former England Under-20 international spent the first half of the season on loan at Charlton Athletic - scoring against Leeds at The Valley in November - and had spells at Burnley and Blackburn last term as a result of slipping down the pecking order at Hull.
Stewart, who was on the books at Manchester United as a youngster, joined Hull in January 2011 on a permanent basis following a loan stint at the KC Stadium.
And McDermott believes signing Stewart represents a coup for the Championship club.
"Cameron fits the bill as the type of player we are looking to recruit here," McDermott said.
"He has pace, he gives us something different, and he is hungry to do well."
