Two goals from Ross Stewart put the hosts in control in the first half while Callum Doyle added a third five minutes before half-time.
Stewart then completed his hat-trick after the break before substitute Benji Kimpioka added a fifth with a neat finish.
Sunderland are now two points ahead of second-place Rotherham, although the Millers have a game in hand.
Our chief SAFC writer Phil Smith has delivered his verdict on how each player fared for Lee Johnson’s side:
A message from the Football Clubs Editor
Our aim is to provide you with the best, most up-to-date and most informative Sunderland AFC coverage 365 days a year.
This depth of coverage costs, so to help us maintain the high-quality reporting that you are used to, please consider taking out a subscription to our new sports-only package here.
Your support is much appreciated. Richard Mennear, Football Clubs Editor
1 / 4