Fellaini has developed into a key member in David Moyes’ Everton squad since joining the club from Standard Liege in 2008.
Fellaini’s previous deal was set to expire in 2013, but the new deal will keep him at Goodison until 2016.
The midfielder has recently been linked with the likes of Chelsea, Manchester City and Real Madrid.
Everton boss Moyes said: “We are all delighted we have secured the services of Marouane for the long term.
“As everyone is aware these negotiations have been ongoing for some time but both parties remained positive that we would reach agreement.
“Marouane has been a hugely influential player for Everton since his arrival in 2008 and we hope that remains to be the case for the next five years.”
