The performance of goalkeeper Mignolet was a significant factor in keeping Stoke at bay, the 24-year-old Belgian producing a string of saves with the best being a point-blank stop to keep out Robert Huth's header.
O'Neill said: "He has been fantastic for us this year. He started on New Year's Day for us when Keiren Westwood was ill and Simon was not particularly fit - in fact he had brought his parents over for the game thinking he was going to be sitting in the stand.
"He played that game with a mask because he had broken his nose and jaw I think, and he has been fantastic since then.
"With age on his side, he should be a really fine goalkeeper."
The result means Stoke and Sunderland have now each drawn six times in the Premier League this season, the former in a total of nine fixtures and the latter in eight with both on nine points.