Mirallas struck 20 times to help Olympiacos win last season's Greek top division and has contributed five goals in all competitions since moving to Merseyside last summer.
"Everybody knows he [Mirallas] has quality," Fellaini explained. "He can score goals and is an important player for Everton. Every game he can contribute and I think he has. I hope for him that he keeps going like this.
"He can dribble and is involved in the action, which is important for forward players. He can score goals and takes good corners, so he is important for the team."