Under the agreement, the terms of which were not disclosed, Marathonbet will assume the role as the club’s betting partner in all countries worldwide, with the exception of China and the US.
Marathonbet will also have access to United’s various digital platforms to engage with the club’s many supporters around the world.
The deal comes after Marathonbet last month also struck up a partnership with United’s Premier League rival Liverpool.
“Manchester United has a global presence with fans all over the world and our partners help us to engage with them in a range of innovative ways. Through our partnership, we hope to bring to fans exclusive content, access to bespoke player and legend interviews as well as competitive betting odds,” Manchester United group managing director Richard Arnold said.
Stan Reoutt, chief executive of Marathonbet, added: “Recently, Marathonbet has made great strides towards being at the forefront of football betting and this partnership cements our aims as a brand.
“Manchester United is one of the most recognisable names in the world, let alone in world football, and this announcement is a clear marker of our global plans for Marathonbet,” he added.