The diminutive Benin international's second goal in a week secured a 1-0 win over Everton on Saturday as the Black Cats followed up their 3-0 derby success at Newcastle.
Sessegnon struck in first-half stoppage-time when he drilled in a low shot past Toffees goalkeeper Tim Howard.
Di Canio said: "The little one is big. He's a big player. We all know he is capable of scoring a goal like that.
"I want to point attention to the job they did once again up front. Both Stephane and Danny [Graham] - they left all their energy on the ground, and then obviously the goal made all the difference. It was a fantastic goal.
"At the end, to be honest, we suffered a bit, but they didn't have any clear chances - apart from the back-pass by Sebastian [Larsson], that was the only one.
"That can happen. But I did much worse when I used to play, so it's not an issue because Seb delivered another fantastic effort in the middle of the field, quality.
"He's one of the best players, not only here, but in the Premier League."