Mourinho became the first United manager in history to win a major trophy in his first season when he secured the League Cup last year, and he also led the club to victory in the Europa League, the only competition they had never won.
But this season they are a distant second in the Premier League to Pep Guardiola’s Manchester City, who are 12 points clear in the table and unlikely to be caught barring a spectacular collapse.
“I am really honoured and proud to be Manchester United manager,” Mourinho, 54, said in a club statement.
“I would like to say a big thank you to the owners and to (executive vice-chairman) Mr (Ed) Woodward for the recognition of my hard work and dedication. I am delighted they feel and trust that I am the right manager for this great club for the foreseeable future.
“We have set very high standards — winning three trophies in one season — but those are the standards I expect my teams to aim for. We are creating the conditions for a brilliant and successful future for Manchester United.”
Woodward said the former Chelsea and Real Madrid boss, whose new deal includes an option for a further year, had already achieved a great deal in his time at Old Trafford.
“His work rate and professionalism are exceptional and he has embraced the club’s desire to promote top quality young players to the first team,” said Woodward.
“He has brought an energy and a sense of purpose to everything that he does and I am sure that will continue to bring results for the fans and the club.”
Earlier this month Mourinho dismissed reports he may walk out on United this coming close season as “garbage”.
Mourinho had looked an unhappy figure as United’s title bid faltered and they suffered a shock League Cup exit at Championship side Bristol City.
There had been suggestions that Mourinho was disappointed at the relative lack of spending power at his disposal, claims which he also denied.
And Mourinho was upset at suggestions that his decision to live in a hotel, rather than finding a home in Manchester, was a sign of a lack of professionalism or commitment to the job.