The former Chelsea manager has reportedly agreed to take over the helm at Old Trafford.
Mourinho, who has been out of work since he was sacked by Chelsea in December, is understood to have agreed a deal in principle to take over the helm before United's 2-1 win over Crystal Palace in Saturday's FA Cup final.
Despite guiding the Red Devils to their first piece of major silverware since the departure of legendary boss Sir Alex Ferguson, Louis Van Gaal now looks to have paid the price for failing to qualify for the Champions League.
The Dutchman, who still has one year remaining on his current deal at Old Trafford, has arguably exacerbated those shortcomings by spending around £250 million on new players.
An announcement confirming Mourinho's appointment could be confirmed as early as next week, bringing a conclusion to weeks of rumours linking him to the job.
While his second spell at Stamford Bridge was brought to an end in turbulent circumstances, Mourinho remains one of the most coveted managers in the game, having won the Premier League three times and the Champions League twice.