Black Cats boss, Roy Keane, told his club's official website: "El-Hadji is a great signing for us and we're thrilled to get him in.
"He has bags of Premier League and international experience, which is exactly what we've been targeting this summer.
"El-Hadji has always been the kind of player opposition teams and supporters love to hate, a thorn in the side and that's why we're delighted to now have him in our squad.
"Our coach, Ricky Sbragia, has also worked very closely with him and speaks extremely highly of him, so we're looking forward to working with El-Hadji,
"I think he's a signing who will excite our supporters."
Good Luck Dioufy!!