Matty Oakley's smartly taken goal in first-half stoppage time had put the visitors on the back foot, but they squeezed the life out of the Rams after the break with Chris Brown and Ross Wallace turning the match on its head in the space of three minutes.
Keane said later that he had said nothing dramatic to his players at half-time but they certainly picked up the pace and once Wallace had put his team in front Derby never looked capable of replying.
It was a time for change at both clubs with Derby making four changes to the team beaten at Colchester while Keane gave debuts to five of his signings.
Much of the first 45 minutes was largely shapeless although Sunderland started brightly only for Derby to take the initiative in the last 15 minutes.
Steve Howard smacked a shot against the crossbar from 25 yards and Giles Barnes should have done better with the rebound and Ryan Smith brought a good save out of Ben Alnwick with a low skimming drive in the 43rd minutes.
Just when it seemed the first half would finish goalless Derby scored when Mo Camara crossed from the left and Howard headed down for Oakley to drive a shot past Alnwick from ten yards.
Sunderland had to defend the opening minutes of the second half with Stanislav Varga picking up a booking for a blatant trip on Barnes and Alnwick was forced to beat out a 25-yard free-kick from Camara.
But Graham Kavanagh and Dean Whitehead exerted their influence in midfield and David Connolly had a great chance to equalise only to completely mis-kick in front of goal.
But an equaliser always looked likely, although it was poor defending that allowed Brown to bundle the ball over the line after Kavanagh had crossed from the left.
The striker was booked for his celebrations with the Sunderland supporters, who had a second goal to savour two minutes' later when Wallace drilled a shot across Stephen Bywater and into the bottom left corner.
Derby had few chances after that, but Sunderland always looked relatively comfortable, although Keane was off the bench near the end to remonstrate with Rory Delap when the full-back needlessly gave the ball away.