The sports channel will rival Perform, which specialise in football, cricket and tennis coverage.
The channel, called GBsport.tv will launch in September this year and claims to steam 1,400 hours of live sports coverage a year.
The core sports GBsport.tv will champion include athletics, badminton, boxing, hockey and rowing.
It will feature a mix of live domestic and international sporting events including national, European and world championships. But its focus will be on domestic sport.
The channel will be accessible to sport fans across a number of multi-media platforms including laptops, mobiles, internet enabled TVs, as well as shared via Facebook.
TMG is providing funding, editorial resources, and will promote it on its website.
The content will be streamed on TMG's website.
TMG is running the digital sports channel in partnership with Convers Sports Initiative, the media and entertainment company, Input Media, the sports production company, and brand engagement company Kameleon Worldwide.
Vladimir Antonov, co-founder of GBsport, said: "We believe GBsport TV is a 'now' idea and will benefit hugely from the growing trend for consumers to watch their favourite sports online."
Rival Perform provides online sports content to third parties.