He announced what was happening on pit road for World Sports Enterprises, and later worked for TBS, TNN (now Paramount Network) and CBS.

As of 2014, Byrnes was the co-host of NASCAR Race Hub on Fox Sports 1 and was expected to be the lead announcer for the Camping World Truck Series in 2015.

However, later that year in September, he was diagnosed with a recurrence of stage 4 head and neck cancer; on October 9, Fox Sports announced that he had decided to take an indefinite leave of absence from work in order to focus on his treatment.

[4] On April 10, 2015, it was announced that, in coordination with Bristol Motor Speedway, Fox, and Stand Up to Cancer, the 2015 Food City 500 would be renamed the Food City 500 In Support Of Steve Byrnes and Stand Up To Cancer; the race would feature tributes to his legacy as a NASCAR broadcaster, along with his 56th birthday, which fell during the week prior to the race.

[5][6] Two days after the tribute race, Byrnes died early on April 21, 2015, of complications from his cancer in Fort Mill, South Carolina, one week after his 56th birthday, and was survived by his wife Karen and son Bryson.

[2][7] In tribute, drivers Josh Wise and Clint Bowyer added photos of Byrnes and his son Bryson to their cars' hoods for the Toyota Owners 400.

[11] Byrnes lived in the Charlotte metropolitan area (where most NASCAR teams are based) with his wife Karen and son Bryson.