The 30-year old USA international has made the move from Premier League club Tottenham to the MLS and is looking forward to achieving plenty of success with the Sounders.
"Seattle, I just want to thank ya'll and the Seattle Sounders organization for making me feel so welcome and at home," Texas native Dempsey told the crowd at his unveiling at CenturyLink Field on the weekend.
"I look forward to getting on the field and playing in front of the best fans in the world. I think we'll accomplish some great things here."
Dempsey scored 60 goals in 225 appearances for Fulham over five-and-a-half years at Craven Cottage and a further 12 for Spurs in his one season at White Hart Lane. He formerly played with New England Revolution in MLS.