The singer needed five stitches after smashing his head on a glass table in a mock fight with bandmate Kian Egan.
Writing on Twitter yesterday, Byrne commented: "Thanks to all who are concerned about the scar on my head! Kian and a security tried to pick me up. But after fending one off I wrestled Kian to the ground and hit my head off a glass table in the process!
"All fun and stupid lads jokin about! Thanks to all in Liverpool A&E! I'm healing already and thanks for all your concerns!"
The 31-year-old then joked that he received "a certificate of bravery" in hospital along with his five stitches.
Speaking of the moment that Byrne was injured, a source told The Mirror: "There was blood everywhere. It looked horrific."
Westlife's current 'Where We Are' tour runs until August.