The Red Devils appointed Mourinho as their new manager in 2016 following disappointing spells under David Moyes and Louis van Gaal.
Mourinho led Manchester United to Europa League and League Cup glory in his first season in charge at Old Trafford.
However, the 20-time English champions finished in sixth spot and a long way behind Chelsea FC in the title race.
Manchester United managed to keep pace with Manchester City in the opening weeks of the season before a 2-1 loss to Huddersfield Town appeared to derail their title challenge under Mourinho.
The Red Devils lost 1-0 to 20th-placed West Brom in the Premier League at Old Trafford last weekend to hand Manchester City the title with five games to spare.
Mourinho masterminded Chelsea FC’s title success in 2014-15 before he was sacked in December 2015 following a disappointing start to their title defence.
Speaking Manchester United’s website about the Premier League title after Manchester City were crowned champions, Mourinho said:
“I trust in my work, that is for sure.
“I have no reason not to trust. The last Premier League title that I won was not 20 years ago, it was three years ago and I know how to win. I believe in myself.”
Manchester United lost 2-1 to La Liga giants Sevilla in the Champions League round of 16 last month following a shock defeat at Old Trafford.
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