The Portuguese boss is in his first season at Old Trafford and has his side battling for Champions League qualification - either through finishing in the top four or more likely winning the Europa League - while already securing the League Cup and Community Shield.
He is charged with bringing back the level of success that has been missing since Sir Alex Ferguson left in 2014 and if he can manage that then he predicts a lengthy stay at club.
"(A minimum of) Three years, I think I will be here, I think the club understood the necessity to give stability to all levels," Mourinho said in an interview with Portuguese TV channel SIC, which has been published in a number of national newspapers.
"I believe if we do that, even without a massive success, which is harder in football, even more so in England, but with some type of success, I see myself staying here if they want me to stay.
"If they want me to stay I will stay, but like I say, we both need to be happy. I'm not a type of person to be at a club 10, 15 years, without real success.
"I need to have true success, my life is like that, I need that pride and happiness. In all honesty, I would like things to go well and be here many years."
United have been the dominant force of the Premier League era, winning 13 titles and two Champions League, but in recent times they have falling down the pecking order and Mourinho reckons they were blind sided by other clubs.
"I think the club got so used to winning and having success, maybe they didn't realise other clubs were growing, even when Sir Alex was in his last years at the club," he added.
"The Premier League were creating conditions for the other clubs to become financially powerful and that has definitely transformed the league.
"Nowadays all clubs have grown and with TV rights being shared, it's almost unique in European football.
"It has allowed that difference in power to be slowly diluted, in a way that Manchester United stopped being the all-powerful Manchester United, and became part of a group of five, six, seven very powerful clubs. They are followed by other clubs, less powerful, but not poor clubs.
Read the full article on eurosport.co.uk: Mourinho wants long-term success at Manchester United