He has been capped at Sevens level by Wales and has built a reputation as an attacking threat with ball in hand who is also solid in defence with a good kicking game.
Thomas has plenty of experience of playing against Gloucester, having played against the Cherry and Whites in the Heineken Cup in 2009-10 and also appeared in the LV= Cup semi final at Kingsholm just over a year ago.
That experience meant that he was able to make an informed choice as he explained to the club website:
"I've played at Kingsholm twice in the last few seasons, once in the Heineken Cup and once in the LV= Cup. Although I was with the opposition, I couldn't help but be impressed by the matchday atmosphere.
"I've also watched a lot of Gloucester matches and they play a great brand of rugby, one that will certainly suit my game and I hope that I can add something to the squad.
"Talking to Bryan Redpath and hearing his plans for the future, I'm excited at the prospect of joining the club."
Meanwhile Redpath explained where Thomas would fit into Gloucester's plans.
"Olly Morgan is obviously recovering from knee surgery and we've been using Jonny May and Tom Voyce in the full back role since Morgs got injured.
"What Martyn will give us is another specialist full back in the squad. He's the sort of player whose style of play should see him fit in well here and we look forward to him arriving in the summer."