Chong’s previous Old Trafford deal was set to expire at the end of the season, with Internazionale initially hopeful of signing him on a free transfer this summer.
But the 20-year-old, who has made 10 appearances for Ole Gunnar Solskjaer’s side this season, will remain at United having joined the club’s academy from Feyenoord in 2016.
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“Tahith works extremely hard every day and he is constantly improving,” said Solskjaer. “His performances this season, whether for the first team or Under-23s, are testament to his hard work, dedication and to his character.
“We are pleased with the progress he has made since he stepped up from the academy and are looking forward to continuing to develop his talent.
“Tahith has great potential; given his age, ability and work-ethic, we can see that he has a bright future at Manchester United.”
Chong said: “When I joined Manchester United as a youngster, it was a dream come true. It is an honour every time I pull on the shirt and represent this club.
“I am working hard every day to improve and I know this is the perfect environment to develop my game. The opportunity to learn from the manager, his coaching staff and the world-class players here is fantastic.
“I am delighted to sign this new contract and really grateful for the chance to prove myself here for many years to come.”