After emerging from Cardiff’s junior ranks, Young joined Gloucester before switching to Wasps in 2014 under his father Dai.
Young returned to the Arms Park from Wasps for the 2022-23 season, where Dai was then in charge.
He will leave Matt Sherratt’s Cardiff, with Dragons boss Tiatia adding: “We’re looking forward to Thomas joining up with us. He’s a talented loose forward with international experience who brings a competitive edge and is someone who will drive standards.
“Thomas is a player who plays at a high level and has a huge influence on games, both in attack and in defence.”
Dragons have not specified the duration of Young’s contract but hope he will help improve their standing in Welsh rugby. They currently lie bottom of the United Rugby Championship amid ongoing struggles on the field.
