Tinne Gilis is one of Belgium's premiere squash players, and has been her nation's No.1 in recent years. She, along with older sister Nele, have been a key fixture of the world's top 25 for a number of years.

She turned professional in 2014, and the year after that, she made her first quarter final appearance on the PSA Tour. However, she was beaten by her sister in the last eight. The same happened in the Paderborn Open in 2016, before she reached the semis of the Harrow Ukrainian Squash Cup. She also made the semis of the Edinburgh Sports Club Open in the early part of 2017.

That was her breakthrough year, as she reached the last four in seven tournaments she played in. This included her first two titles on the PSA Tour. Gilis had to wait until the October to secure her first crown, which came after beating Enora Villard in the final of the Val de Marne. The Belgian then beat Haley Mendez to win the International D’Italia two months later.

2018 was more of a barren year for the youngster, as she only managed quarter final appearances in three tournaments; the Irish Squash Open, Tournament of Pyramides and the Open International de Squash de Nantes. The younger of the Gilis sisters made it to the last eight of the J Warren Young Memorial Texas Open and the Cannon Kirk Irish Open in the first half of 2019, as well as breaking into the World's top 30 for the first time in her career.

The young Belgian made her way into the top 20 in the World Rankings for the first time during the 2019-2020 campaign, joining her older sister Nele in that bracket. This was down to reaching the last 16 of the PSA Women’s World Championship for the first time, along with a quarter-final appearance at the PSA Bronze level Bahl and Gaynor Cincinnati Cup.

She also reached the last 16 of her final three events of 2020, the Manchester Open, CIB Egyptian Open and the CIB Black Ball Squash Open. That run continued into the start of 2021, as Gilis made it to the third round of the CIB PS Black Ball Squash Open in March. Later that year, the Belgian reached the last eight of the Manchester Open, and the semi-finals of the Bronze level DAC Pro Squash Classic.

She started 2022 with a semi-final appearance at the Cleveland Classic and a quarter final result at the Cincinnati Gaynor Cup, before then going on to reach a first Platinum level quarter final, as she went all the way to the last eight at the Allam British Open.

That kicked off a run which saw her move to her highest ever World Ranking, as she then won two Challenger 30 level events in the space of three weeks. Gilis won both the Annecy Rose Open and the Cannon Kirk Irish Squash Open in April to move up to World No.13. She then made the last eight of the El Gouna International before finishing runner-up at the RMCLUB Women’s Open Presented by Expression Networks in Mauritius, her last appearance of the season.

In the summer of 2022, Gilis took the European Individual Championships crown, before starting the new PSA World Tour season by reaching the final of the Open de France de Squash, where she was beaten by older sister Nele. She ended the year with a semi-final appearance at the Barfoot & Thompson New Zealand Open and she also made it into the last eight of the MARIGOLD Singapore Squash Open.

The Belgian claimed her first PSA World Tour title in the early part of 2023, as she lifted the Bronze level Squash On Fire Open trophy, her biggest Tour title to date. She followed it with a win at the Challenger 30 level Richmond Open, along with reaching the quarter finals of the El Gouna International for the second year in succession, to end her 2022-2023 campaign on a high.