The operator recently announced agreements with FC Barcelona and Liverpool FC, acting as global betting partner for both.
The deal with Chelsea aims to increase brand awareness in the UK and around the world, according to a statement from the club.
Chris Townsend OBE, Chelsea Commercial Director, said: "We are excited to welcome 1xBet to Chelsea Football Club as our new global betting partner."
Alex Sommers, spokesman of 1xBet said: "It’s a big honour for us to become a partner of such a great football club as Chelsea.
"We guarantee Chelsea fans will see a variety of interesting and engaging activities from the partnership over the next three years."
William Hill was the club’s partner for the last three years.
