The Dutch defender's arrival was confirmed by the west London outfit soon after the Cottagers announced the Switzerland international's deadline day move to La Liga.
Senderos' departure from Craven Cottage was confirmed by the west Londoners on Friday, with news of the former Toffees player's arrival announced soon after.
Dutch defender Heitinga has signed a deal until the end of the season, having fallen out of favor at Goodison Park.
He told Fulham's official website: "I'm really pleased to get the move completed and I'm looking forward to playing my first game. I think it's a good move for myself and I'm looking forward to meeting my teammates. I've spoken already with (head coach) Rene Meulensteen and I think it's the right club for me.
"I chose Fulham because the feeling was good and what was also important was the conversation between me and Rene. He knows exactly what he wants and I know exactly what I want. The main thing is to keep Fulham in the league and hopefully the boys will start with a win against Southampton."
Everton boss Roberto Martinez added: "Johnny has left with our best wishes and we hope everything goes as planned and he can get in the (Netherlands) World Cup squad.
"He (Heitinga) has been a terrific servant and we wish him well."
Heitinga joins Fulham with the club 19th in the Premier League, having played 140 times for Everton following a move from Atletico Madrid in 2009.
Senderos arrived at Craven Cottage in the summer of 2010 and went on to make 68 appearances for the club.
The Switzerland international appeared on 12 occasions in the Premier League this season, scoring in the 4-1 win at Crystal Palace in October.