Emmylou Harris, The Infamous Stringdusters, Greensky Bluegrass and more are set to take the Mill Spring stage in September.
The Outer Banks and Nashville star is currently readying his debut studio album.
They join the already announced headliners, Kane Brown and Chris Stapleton.
Combs’ shows will be also feature a special writer's round with Ray Fulcher, Drew Parker and James McNair.
A list of the 10 best things to see at Country 2 Country festival in London, Glasgow and Dublin in March
In April, the Oklahoma hitmaker will be heading to the UK, Ireland, the Netherlands, Germany and Denmark.
