Thomis was born in the commune of Colombes, a northwestern suburb of Paris, to parents of Martiniquaisheritage. She began her sporting career training as a sprinter and long-distance runner.[4] At the age of 13, Thomis began playing football after attending a trial for women footballers in Épinay-sur-Seine.[2][4] After successfully playing for the local club, she joined Football Club Feminin de Colombes in her hometown. In 2002, Thomis was selected to attend CNFE Clairefontaine, the women's section of the Clairefontaine academy. She spent three years training at the facility alongside future domestic teammates Louisa Necib, as well as future international teammates Caroline Pizzala, Élise Bussaglia, and Laure Lepailleur.[4] In three seasons at the academy, Thomis played in over 50 matches scoring 32 goals.
Montpellier and Lyon
After departing Clairefontaine, Thomis joined Division 1 Féminine club Montpellier. Necib later joined the club the following year. In her first season with the club, Thomis appeared in 20 league matches scoring three goals as Montpellier finished runner-up in the league to Juvisy. She also made her European debut participating in the 2005–06 UEFA Women's Cup. In the team's first leg quarter-final tie against Danish outfit Brøndby IF, Thomis scored a double, which, after a positive result in the second leg, allowed Montpellier to advanced to the semi-finals where the club was eliminated by the eventual champions 1. FFC Frankfurt.[5] Thomis' goal output increased in the 2005–06 season scoring 15 goals in 22 matches as Montpellier claimed the Challenge de France, the women's domestic cup in France. After the season, in June 2007, rival D1 Féminine Lyon confirmed that both Thomis and Necib would be joining the club for the 2007–08 season. In her debut season at Lyon, she played in 17 league matches scoring seven goals helping the club win the league and cup double. In the 2008–09 season, Thomis appeared in 17 total matches scoring 14 goals as Lyon won the league for the third consecutive season and reached the semi-finals for the second straight season in the UEFA Women's Cup.
In the ensuing two seasons, due to injuries, Thomis was limited to only 30 appearances domestically. The striker did scored 17 goals in that span. In the re-branded UEFA Women's Champions League, Thomis made eight appearances scoring three goals as Lyon reached the final in the 2009–10 edition of the competition. Lyon was defeated by German club Turbine Potsdam in the penultimate match. In the 2010–11 edition of the Champions League, Thomis was a part of the team that won the competition defeating its nemesis Turbine Potsdam 2–0 in the final.
She left Lyon and retired after the 2017/18 season.[6]
