Roman Abramovich has been added to the UK government's sanctions list by Foreign Secretary Lis Truzz amid Russia's invasion of Ukraine.
Abramovich has now seen all of his UK assets, including Chelsea Football Club, frozen.
This means that the Blues will be allowed to continue functioning but under considerable restrictions under a special sporting licence that will expire at the end of May.
The owner of the reigning champions of Europe will no longer be permitted to invest in the club, any prize money earned will be frozen and fans will not be allowed to attend any away games.
Chelsea had been put up for sale last Wednesday by Abramovich.
The 55-year-old has always denied any association with Russian president Vladimir Putin but the government has now stated explicitly that the billionaire has been an associate "for decades".
The sanction read: “[Abramovich] is associated with a person who is or has been involved in destabilising Ukraine and undermining and threatening the territorial integrity, sovereignty and independence of Ukraine, namely Vladimir Putin, with whom Abramovich has had a close relationship for decades.
"This association has included obtaining a financial benefit or other material benefit from Putin and the government.”
Abramovich was looking to sell the club as quickly as possible and had set a deadline of March 15 for potential buyers to register their interest, with a consortium led by US billionaire Todd Boehly understood to have registered a formal bid.
However, as long as he is on the sanctions list, the west London club's ownership is not allowed to change hands unless special dispensation is granted by the government, something that would mean the current owner doesn't earn a penny.
According to the BBC, the Russian paid just £140million to acquire the club from Ken Bates back in 2003, with some reports claiming the Blues are now worth 20 times that.
