Jana Fett

On the ITF Junior Circuit, Fett had a career-high ranking of No. 12, which she achieved on 24 February 2014. She was the runner-up at the 2014 Australian Open girls' singles event, wherein she fell to Elizaveta Kulichkova in the final.

Fett's biggest title to date was at the 2015 Dunlop World Challenge, where she won the singles title, defeating Luksika Kumkhum in the final.

At the 2017 Hobart International, she qualified for her first main draw of a WTA tournament.^[] She reached her first WTA Tour semifinal but lost to eventual champion and fellow qualifier, Elise Mertens.

Later in the year, she reached her second semifinal at the Japan Women's Open, again coming through qualifying, while also scoring her first victory over a top-20 player, the top seed Kristina Mladenovic. She lost to fellow qualifier Miyu Kato, after failing to convert a match point.^[] As a result, she made her top 100 debut on 18 September 2017.

At the 2018 Australian Open, she appeared in the Grand Slam main draw for the first time as a direct entry and recorded her first major win over Misa Eguchi. In the second round, she played against second seed Caroline Wozniacki and had two match points, leading 40/15 at 5–1 in the third set. However, she lost that game and the successive five games to yield the match.^[]

She qualified for the main draw of the 2022 Wimbledon Championships after three years of absence at the All England Club where she lost to world No. 1, Iga Świątek.

She reached the final at the WTA 125 2023 Midland Tennis Classic but lost to first-time WTA Challenger titlist Anna Kalinskaya.

In April 2024, Fett won the biggest title in her career at the W100 Oeiras Open. On her debut at the French Open, she entered the main draw as a lucky loser and recorded a first round win over Jéssica Bouzas Maneiro, then losing her next match to Marie Bouzková.

At the Jasmin Open, Fett reached the second round defeating Mayar Sherif before losing to Sara Sorribes Tormo in three sets. The following week at the 2024 Thailand Open 2, she reached the quarterfinals after defeating Zheng Saisai and eighth seed Varvara Gracheva by retirement, before going out to eventual champion Rebecca Šramková.

She entered the main draw of the WTA 1000 China Open as a lucky loser making her debut at this level and recorded her first WTA 1000 win over wildcard Wang Meiling. Fett lost in the second round to ninth seed Daria Kasatkina.