Masuaku departed Turkish side Besiktas at the end of the last campaign after three years with the club, one of which included a season-long loan from West Ham United. 

But the 31 year-old arrives back in the Premier League two years after swapping West Ham for Besiktas, and provides the Black Cats with top-flight experience in defence. 

The DR Congo international made 105 appearances in the Premier League during his seven-year stint with the Hammers. 

Masuaku will provide competition at left-back with Dennis Cirkin, with the latter being Regis Le Bris' first choice during their promotion-winning campaign in 2024-2025. 

He becomes Sunderland's tenth summer signing ahead of the Black Cat's first top-flight season since the 2016-2017 campaign.

Habib Diarra, Simon Adingra, Enzo Le Fee, Chemsdine Talbi, Noah Sadiki, Granit Xhaka, Robin Roefs, Reinildo and Marc Guiu have also sealed moves to the Stadium of Light. 

Sunderland will be hoping to avoid relegation in its first season back in the Premier League, with Masuaku and Xhaka notably providing important top-flight experience. 

Sunderland gets its Premier League campaign underway next Sunday, when it takes on Masuaku's former club West Ham at the Stadium of Light.

Masuaku spoke about his move to the Black Cats, saying: "I'm excited to be here, and I'm also really happy to be back in the Premier League.

"I want to bring a winning mentality and joy to the fans, and I'm excited to get started."