Martial, 23, has made 162 appearances and scored 46 goals since making his debut for the club against Liverpool in September 2015.
Anthony Martial said:
“I am loving my time at this club. From the day I joined I have been made to feel part of the United family and I have been incredibly humbled and overwhelmed by the warmth and love of our fans, who continue to amaze me with their support.“I would like to thank Ole and his coaching staff for their belief in me and for helping me to take my game to the next level.