Fellaini, who scored his first goal of the season during the Tuesday’s League Cup win over Hull City, signed a four-year deal with the option of a further year when he joined from Everton for 27.5 million pounds ($33.7 million) in 2013.
“Manchester United have confirmed a clause has been triggered in Marouane Fellaini’s contract to extend his stay with the club,” the club said on its website (www.manutd.com).
The 29-year-old was booed by his own supporters having conceded a late penalty during a 1-1 draw at Everton in December and has drawn criticism for his performances in the first half of the season.
Fellaini’s running celebration towards manager Jose Mourinho on Tuesday seemed to be a show of recognition for the faith shown in him after a difficult period.
United, who are sixth in the Premier League, will be looking for their ninth successive win in all competition when they host second-placed Liverpool on Sunday.