The three-time Emmy Award nominee is best known for his work on HBO's series "Entourage," which is wrapping up its eighth and final season this summer.
Zap2it.com described "Gentleman" as a buddy comedy about two former high-school classmates with completely different personalities and outlooks on life.
Hornsby wrote the pilot and will star in it. He also will serve as co-showrunner with "Friends" executive producer Adam Chase, Zap2it.com said Friday.
Swim Week Miami Beach 2014 [PHOTOS]