Thomas began his professional rugby career in 2012 playing for Biarritz Olympique during the 2012–13 Top 14 season. He made his French Top 14 debut against Toulon on 9 March 2013, coming off the bench during the final 10 minutes of the 50–15 thrashing. He went on to play a further four matches that season, earning his first start against Grenoble on 29 March 2013. He scored four tries in his debut professional season, picking up a double against Perpignan and Stade Français, while also making a break in the dying minutes of the Stade Français, to set up a try for Takudzwa Ngwenya. During that season, he also made his European debut in the 2012–13 Heineken Cup - though he made his debut against Gloucester in the 2012–13 European Challenge Cup after Biarritz dropped down from the leading tier. He scored two tries on his European debut, causing all sorts of problems for his opposite defender Charlie Sharples. In his second year with Biarritz, he appeared 20 times, only acting as a substitute just once that season. His team failed to impress on the European stage, finishing second in its pool in the 2013–14 European Challenge Cup, while in the French League, finishing last in the table with just five wins. By virtue of finishing last, Biarritz were relegated and Thomas was released from his contract. On 6 June 2014, Racing Métro announced the signing of the promising winger for the 2014–15 Top 14 season.[2] He made his debut in Round 2 of the season, starting in the 30–21 loss to Bordeaux Bègles, and scoring a try on his Racing Métro debut.
Thomas has played for France through age grade level and senior level. He was part of the France U18s side that participated in the 2011 European Under-18 Rugby Union Championship in France, finishing fourth behind Ireland, England and Wales. He also played for the France U20s team during the 2013 Six Nations Under 20s Championship - finishing fifth with two wins, and played in the 2013 IRB Junior World Championship in France. Though at home, the French U20s team finished third in their pool, and set up a quarter-final against Ireland U20s, winning 9–8. They challenged Argentina U20s in the 5th place game, in which Thomas scored two tries to help France secure a 37–34 win and an overall 5th place.
His form and try scoring ability earned him a call-up to the France national team by Philippe Saint-André for their 2014 November test series against Fiji, Australia and Argentina.[3] He made his debut against Fiji, starting on the left wing, and scoring within the first minute of the match. He then went on to score a further two tries, which came just 2 minutes apart from each other.[4] Although injured in the first game of the 2015 Six Nations he did receive a KS winners medal.
| # | Date | Venue | Opponent | Result
(FRA–Opponent) | Competition |
| 1 | 8 November 2014 | Stade Vélodrome, Marseille, France |  Fiji | 40–15 | 2014 November test series |
| 2 |
| 3 |
| 4 | 15 November 2014 | Stade de France, Saint-Denis, France |  Australia | 29–26 | 2014 November test series |
| 5 | 11 November 2017 | Stade de France, Saint-Denis, France |  New Zealand | 18–38 | 2017 November test series |
| 6 | 3 February 2018 | Stade de France, Saint-Denis, France |  Ireland | 13–15 | 2018 Six Nations |
| 7 | 11 February 2018 | Murrayfield, Edinburgh, Scotland |  Scotland | 26–32 | 2018 Six Nations |
| 8 |
| 9 | 17 November 2018 | Stade Pierre-Mauroy, Lille, France |  Argentina | 28–13 | 2018 November test series |
| 10 |
| 11 | 9 February 2020 | Stade de France, Saint-Denis, France |  Italy | 35–22 | 2020 Six Nations |
| 12 | 24 October 2020 | Stade de France, Saint-Denis, France |  Wales | 38–21 | Test Match |
| 13 | 28 November 2020 | Stade de France, Saint-Denis, France | Italy | 36–5 | Autumn Nations Cup |
| 14 | 6 February 2021 | Stadio Olimpico, Rome, Italy | Italy | 50–10 | 2021 Six Nations |
| 15 |
