The 29–year-old Austrian was brought in from Bayern Munich after Christian Eriksen picked up an ankle injury in the FA Cup tie against Reading last January which was to keep him out for two months.
Sabitzer went on to make 18 appearances, scoring three goals.
He came on as a sub at Wembley in both the EFL Cup win over Newcastle and FA Cup semi-final triumph over Brighton scoring one of the penalties in the shoot-out.
A United statement said: “Everyone at the club is disappointed to lose Marcel’s services, as the Reds chase a strong finish to the season in the Premier League and FA Cup, and we are grateful for his contribution to our progress so far.”
A permanent deal for the player is not expected as he prepares to return to Germany.
Sabitzer, however, has enjoyed every moment of his time at Old Trafford and is open to committing his future to the Premier League giants.
He told Bild: “United made it clear that it was a project until the summer, then we’ll see.
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“Until then, I want to give everything here.
“It’s a loan deal without an option. In the summer, the situation will be evaluated
“But I can say that I found my place here.
“Now I know the Premier League and can say there’s nothing better, more intense and tougher.
“Every game is a fight. It’s the best league in the world. When you play once here you know it’s incomparable
“Of course, my thoughts are on United, especially with the trust I get from Erik ten Hag – it’s very positive.
“But I’m not the only one who decides.
‘There’s competition at every top club. At United, it’s even more extreme than in Munich.
“Here there’s [Scott] McTominay, [Christian] Eriksen, Casemiro, Fred and me.
“If I was afraid of competition, I wouldn’t have joined either Bayern or United.”
United, meanwhile, are still assessing the severity of Marcus Rashford’s injury and whether he will return to action for this weekend’s trip to Bournemouth.
He was ruled out of Saturday’s 2-0 home win over Wolves with what manager Erik ten Hag would only describe as a ‘leg injury’ with the club refusing to expand further on the problem.