Mourinho, whose family home is in West London, has signed up to play in Game 4 Grenfell.
But he has been named on the bench by ex-Newcastle star Alan Shearer.
Former West Ham and Portsmouth keeper David James starts between the sticks for #TeamShearer.
Evening Standard journalist Vaishali Bhardwaj captured footage of Mourinho warming up.
The 54-year-old displays his reflexes by stopping a couple of shots.
Game 4 Grenfell: Kick-off time, TV channel and team news for Loftus Road event
Marcus Mumford, who skippers Les Ferdinand’s team, revealed the news about Mourinho on Instagram.
He said: “Ladies and gentlemen I have some huge transfer news ahead of Game 4 Grenfell at Loftus Road tomorrow.
“The great Jose Mourinho, resurrecting his professional career, has just signed for Team Shearer.”
Mourinho failed to make the grade as a professional footballer in Portugal in the 1980s.
He played a handful of games for Rio Ave, Belenenses, Sesimbra and Comercio e Industria before calling it quits.
Ex-footballers and celebrities are coming together at Loftus Road this afternoon in aid of those affected by the Grenfell Tower disaster.
The fire at Grenfell Tower on June 14 claimed the lives of at least 80 people.
