Fucsovics's first major success came in 2009, when he won the US Open Boys' Doubles title, with Hsieh Cheng-peng of Chinese Taipei.
1 in the ITF Junior Rankings in July 2010 and as a result entered the Youth Olympics as tournament's top seed.
His success at Ilkley saw him win a wildcard into 2017 Wimbledon Championships main draw where he lost to the 16th seed Gilles Müller in the opening round.
In September 2017 he played a pivotal role in Hungary's promotion to the World Group winning 3 rubbers against favorites Russia.
[4] Ranked 80 at the Australian Open, he won his first match in a Grand Slam main draw by defeating Radu Albot in the first round.
[7] Representing Hungary in the Davis Cup tie against Belgium, Fucsovics lost both of his matches to Ruben Bemelmans and David Goffin.
As the top seed at the Hungarian Challenger Open, he made it to the semifinals where he was defeated by Nicola Kuhn.
[11] Seeded sixth at the Hungarian Open, he was eliminated in the first round by German lucky loser Yannick Maden.
[16] In the semifinals, he beat sixth seed, Steve Johnson to reach his first ATP singles final.
[31] Seeded 29th at the Miami Open, he was beaten in the second round by qualifier Félix Auger-Aliassime, who would end up reaching the semifinals.
[45] Seeded fifth at the Generali Open Kitzbühel, he lost in the first round to eventual finalist Albert Ramos Viñolas.
[46] Starting his US Open series at the Rogers Cup in Montreal, Fucsovics lost in round one to Cam Norrie.
[54] As the top seed at the first edition of the Bendigo Challenger, he retired during his second-round match against Andrea Vavassori due to an ankle injury.
[57] Making it past qualifying at the Rotterdam Open, Fucsovics was eliminated in the first round by sixth seed and world No.
[60] Representing Hungary in the Davis Cup tie against Belgium, he wom both of his matches beating Kimmer Coppejans and Ruben Bemelmans.
[62][63] When the ATP tour resumed tournament play in August, Fucsovics competed at the Western & Southern Open.
This event usually takes place in Cincinnati but this year, it was held at the USTA Billie Jean King National Tennis Center in New York City in order to reduce unnecessary player travel by centralizing the tournament and the subsequent US Open in the same venue.
Getting past qualifying, he reached the biggest final of his career; he ended up losing in the championship match to fourth seed and world No.
At the Qatar ExxonMobil Open, he was forced to withdraw from his quarterfinal match against third seed and defending champion, Andrey Rublev, due to a lower back injury.
[94] Ranked 41 at the US Open, he fell in the first round to Andreas Seppi, despite having five match points in the fifth-set tie-breaker.
[114] In Miami, he was defeated in the second round by 14th seed, rising star, and eventual champion, Carlos Alcaraz.
Fucsovics retired during his final round of qualifying match against Dušan Lajović at the Italian Open.
[121] At the Halle Open, he retired during his first-round match against seventh seed Roberto Bautista Agut.
[127] After the US Open, Fucsovics represented Hungary in the Davis Cup World Group I tie against Ukraine.
88 on 5 December 2022 after winning the 2022 Slovak Open and reaching the semifinals of the 2022 Internazionali di Tennis Castel del Monte in his last two tournaments of the season.
Fucsovics started the season strong winning his sixth Challenger title at the 2023 Canberra Tennis International where he defeated in the final Swiss Leandro Riedi, who came from a 15-match unbeaten streak.
At the Australian Open, after beating Federico Coria and Lloyd Harris, the Hungarian reached the third round where he was defeated by world No.
At the 2023 Italian Open he reached the third round for the first time at this Masters 1000, defeating Filip Krajinović and upsetting 17th seed Alex de Minaur.
[130] At the 2023 BOSS Open he reached back-to-back quarterfinals as a qualifier defeating Denis Shapovalov and Wu Yibing.
[136] For the first time in his career Fucsovics failed to win a match in any of the four Grand Slam tournaments of the season.