The 54-year-old is only halfway through a three-year contract, but the Old Trafford hierarchy are seemingly prepared to place their long-term faith in the Portuguese after they started to challenge on both the domestic and European front.
According to The Sun, United are prepared to hand Mourinho a deal until 2022, which is said to be worth £65m over the course of his contract.
The improved terms are said to be a reward for United sitting joint-top of the Premier League table with rivals Manchester City, with both teams unbeaten after seven fixtures.
The English giants only finished in sixth place last season, but Mourinho was still able to deliver both the EFL Cup and Europa League.
Since arriving at the club in May 2016, Mourinho has taken charge of 75 games in all competitions, winning 46 and losing just 10.