The Italian was appointed with seven matches remaining and was able to keep Sunderland in the Premier League with a three-point cushion over 18th-placed Wigan.
Di Canio has also fined seven players during his short reign at the Stadium of Light, which has sparked an investigation from the Professional Footballers' Association.
"It is clear that we have to bring in players over the summer - half a dozen, maybe more," Di Canio told the Sunderland Echo. "We finished near the relegation zone, and so it is obvious that we need to make changes to make sure that we are not in this situation next season.
"But at the same time we already have some quality players here, and I want them to stay."
Sunderland goalkeeper Simon Mignolet has been linked with a move to Arsenal this summer, but Di Canio wants the Belgian to remain at the club.
"I want to build something here at Sunderland and take the club forward - that is my mission. So the last thing I want to do is to let any of our quality players leave," Di Canio said. "Simon is a top class goalkeeper. He's very important to us."