Martial will join Sevilla’s title charge in Spain, with the club in second place and trailing Real Madrid by four points.
The 26-year-old told United’s interim coach Ralf Rangnick that he wanted to leave in January after growing frustrated with a lack of playing opportunities.
Rangnick then accused Martial of refusing to travel to a game against Aston Villa earlier this month, a claim Martial refuted.
He made his first appearance under Rangnick as a substitute against West Ham last weekend and contributed to Marcus Rashford’s winning goal, after being jeered by some United fans when he came on.
“He’s a great player, one of the best strikers in the Premier League, but we have other players in his position. It’s his wish that he wants to leave,” Rangnick said on Saturday.
Martial was one of the brightest prospects in Europe when United signed him for a then world record fee for a teenager in 2015.
After a promising first season under Louis van Gaal, the Frenchman struggled to impress Jose Mourinho during his two-year spell at Old Trafford.
Ole Gunnar Solskjaer’s appointment rekindled Martial’s career in Manchester and he enjoyed his best goalscoring season in 2019/20, netting 23 goals.
But a long-term knee injury saw him miss the second half of last season and he fell down the pecking order after the signings of Cristiano Ronaldo, Edinson Cavani and Jadon Sancho.
He has scored only one goal in 11 appearances this term but could be an astute signing for Sevilla if he can recover his goalscoring form under Julen Lopetegui in Spain.
Sevilla have been hit by a number of injuries to key players, including their top scorer last season, Youssef En-Nesyri.
They will also be among the favourites to win the Europa League, particularly as the final will be played at their own Ramon Sanchez Pizjuan stadium in May.
Martial will hope the switch can also revive his hopes of playing for France at the World Cup in Qatar later this year.
A knee injury scuppered his chances of being included in the French squad at the European Championship last summer while his lack of form meant he was also left out of the last squad in November.