The 26-year-old has been integral for Sunderland since joining, with the club still in the Championship, on an initial loan from Roma in January 2025.
Le Fee has impressed so far this season, scoring two goals and providing one assist in his six games across all competitions.
Now, Sunderland have confirmed that the midfielder has penned a fresh five-year contract with the club, rewarding him for his fine form.
"I'm really happy to have signed a new contract with Sunderland," Le Fee told the club's website, having agreed fresh terms to run until 2031.
"From the moment I arrived, I've felt the passion of the supporters and the ambition of everyone at the club – I've loved my time here.
"We've achieved something special together over the past couple of seasons, but I believe this is just the beginning.
"I feel very settled here and I'm excited to continue developing, competing at the highest level and helping the club move forward.
"I'm very proud to wear the Sunderland shirt and I can't wait to see what we can achieve together in the years ahead."