The star posted a picture of the dark green Land Rover Discovery on social media today and asked his followers to keep an eye out for it.
The actor, who lives in Petersham, south-west London, and also has a home in the Cotswolds, said the car was “stolen from outside my house”. He later deleted his tweet.
A Met spokesman said police were called at 9.15am today “to reports of a vehicle stolen from outside a residential address in Petersham”. He said no arrests had been made and “inquiries into the circumstances continue”.
Grant is best known for his role in the cult film Withnail & I and several fans replied with lines from the movie telling the actor the thieves “will rue the day” they stole the car.
Another fan, Kody Bramhall, said: “Who would do such a thing? You’re literally the nicest person left in Hollywood.”
Grant, who also appeared in Spice World, Gosford Park and The Iron Lady, was nominated for an Oscar for his role in Can You Ever Forgive Me?
He will hit screens again next month in Star Wars: The Rise Of Skywalker.
According to figures from stolen vehicle recovery service Tracker, the Land Rover Discovery is one of the most stolen cars in the UK.
Police have previously revealed how gangs of car thieves have stolen Land Rovers and sold them on the black market in Africa.