El Pais have reported that the former Chelsea manager signed a pre-contract agreement with the Old Trafford giants last month.
According to the report, Real Madrid were in talks to bring the Portuguese back to Santiago Bernabeu this summer but conversations between the Spanish giants and Jorgen Mendes (Mourinho’s agent) stopped towards the end of January.
It seems that Manchester United have moved swiftly to secure their next managerial appointment.
Mourinho has apparently signed an agreement with United and if he decides to break it before taking over, he will need to pay a penalty.