The Stadium of Light club have received a reported £9million from Premier League rivals Liverpool for the Belgium international, who was their Player of the Season in 2012/13.
Fans have been worried by the departure of star man Mignolet but head coach Di Canio has taken steps to try and ease those concerns.
The Italian is planning a summer overhaul of the squad he inherited from Martin O'Neill in the latter stages of last season and he is ready to use the Mignolet cash.
"Our aim is to build a competitive squad for the new season and this [Mignolet] deal will give us further ability to strengthen the side," Di Canio is quoted as saying by The Guardian.
"I would like to assure our fans that there is a huge amount of work going on behind the scenes."
Sunderland have been linked with Le Havre full-back Benjamin Mendy and Inter Milan midfielder Alfred Duncan.