The partnership will offer Mirror readers a number of exclusive deals and incentives including free bets and bespoke odds.
It will launch in early June, prior to the kick-off of the Euros on 8 June.
Olly Raeburn, retail marketing director at Gala Coral, said: "The7stars has created an exciting campaign which ticks all the boxes for Gala Coral. It's focused on one of the most talked about sporting events of the year and will put us directly in front of eyeballs within our key target audiences."
Liam Mullins, head of press at the7stars, said: "The Mirror is known for its great football coverage, so it's a perfect fit for Gala Coral in order to reach football fans during Europe's biggest footballing event."
Mark Field, head of business development at Mirror Group Advertising, added that the partnership is a great example of how "collaborative thinking creates excellent engagement with readers."