The England midfielder agreed a three-year deal with the Craven Cottage club and moved across London to join Martin Jol's Cottagers for an undisclosed fee.
Parker, 32, moved to White Hart Lane from West Ham in August, 2011.
He made 34 appearances in a successful first season but was blighted by injury last term.
Parker returned to first team action in December and went on to make 29 appearances in all competitions but was surplus to Andre Villas-Boas's midfield plans this campaign.
Parker said: "I'm delighted to be joining Fulham and I'm looking forward to meeting my new team-mates at training tomorrow morning.
"Fulham is an established Premier League club and I look forward to trying to help the team progress even further over the next three years.
Dutchman Jol said: "I'm delighted that Scott has joined us. He's a midfielder who works tirelessly for his team and is a fantastic player both on and off the ball.
"It is wonderful to see a player of his stature playing for Fulham Football Club as he has shown his qualities in the Premier League and for the England team for many years. I'm happy that he's here and joins us for training ahead of our first home match of the season."