Three said on Thursday that they are immediately terminating their £40 million-a-year jersey sponsorship arrangement with Chelsea.
This comes on the heels of the sanctions levied against Blues owner Roman Abramovich.
The Russian billionaire's assets in the United Kingdom have been frozen in response to his country's escalating invasion of Ukraine.
The 55-year-old, though, continues to deny any ties to Russian President Vladimir Putin.
With immediate effect and until further notice, the Three emblem will be removed from Chelsea shirts and advertising boards around Stamford Bridge.
Since the start of the 2020-21 season, they have been the club's primary jersey sponsor.
"We recognise that this decision will have an effect on the many Chelsea fans who are devoted to their team. However, we believe that, in light of the circumstances and the existing Government sanction, it is the appropriate course of action," a statement read in part.