The 34-year old Zaire-born Swiss international has joined the Sounders on an 18-month contract and is sure to bring his consistent European goalscoring record with him to MLS.
Seattle general manager Adrian Hanauer was delighted to announce Nkufo as the club's latest addition.
"He's big, strong, powerful, can hold the ball extremely well in the box, good technically. He is a natural goal scorer and has a nose for the goal,'' Hanauer said. "He's slightly different than some of our guys today. Blaise is a pure, experienced, successful goal scorer.''
Head coach Sigi Schmid echoed Hanauer's sentiments, saying: It's something that is going to make our team better down the line. He's an experienced player. He wants to be here, which is important as well. He's got a history of scoring goals.''
Nkufo, who has enjoyed an extensive career with clubs including Lausanne, Grasshoppers, Lucerne, Mainz and Hannover, was excited about his new challenge.
"Sometimes you have to go with your feeling and the time I spent there I had a good feeling,'' Nkufo said. "The people I met give me a lot of confidence for the future.''