His father, Nodar, is a dancer of the Sukhishvili Georgian National Ballet, his mother, Natalia, worked as a physician.

[8] Tbilisi court released Basilashvili on a bail of 100,000 Georgian Lari (around US$36,300) after his first arrest, however he since attended a trial hearing remotely.

[10] Basilashvili was cleared of charges after court judge questioned why Dorokashvili did not come forward earlier[11] and stated that all claims were either debunked or had no substantial evidence of having happened.

[15][16] In 2008, Nikoloz won his only junior title, the G4 Tennis Express tournament, defeating Raymond Sarmiento in three sets.

The Georgian played mostly at G1 and GA tournaments that year, breaking through the qualifiers of the Eddie Herr Tennis Championship and the Orange Bowl.

He also managed to qualify for Wimbledon later that year, where he beat Facundo Bagnis and 15th seed Feliciano López, advancing to the third round of a major for the first time in his career.

Later that same year, in July, Basilashvili reached his first ATP tournament final – the Austrian Open Kitzbühel, where he lost to Paolo Lorenzi in two sets.

He recorded his first win over a Top 10 player in October when he defeated world number 10 Tomáš Berdych at the Vienna Open.

Basilashvili continued his good form at the Memphis Open, where he defeated 1st seed Ivo Karlović and went on to subsequently reach the final, losing to Ryan Harrison in straight sets.

At the 2017 French Open, after defeating Gilles Simon and Viktor Troicki, Basilashvili lost to eventual champion Rafael Nadal in the third round, winning just one game in three sets.

[20] In October 2018, he won his second ATP title by upsetting top seed Juan Martín del Potro in the final of the China Open.

In December in Doha, he lost to Novak Djokovic in three sets after beating Albert Ramos Viñolas and Andrey Rublev.

At the ATP 500 tournament in Rotterdam in February, as the 9th seed, he beat Hyeon Chung before losing to Márton Fucsovics.

He then played the 2019 Dubai Tennis Championships where he beat Karen Khachanov and Roberto Bautista Agut before falling to Borna Ćorić of Croatia.

At the 2019 Miami Open he reached the fourth of a Masters 1000 for the first time in his career where he was defeated by qualifier Félix Auger-Aliassime.

In July, Basilashvili successfully defended his Hamburg title, saving two match points against Alexander Zverev in the semifinal and beating Andrey Rublev in the final.

[26] Georgia ended third in Group B. Seeded 26th at the Australian Open, he lost in the second round to 2009 semifinalist, Fernando Verdasco, in four sets.

[29] Representing Georgia in the Davis Cup tie against Estonia, he won his match over Vladimir Ivanov.

[37] His semifinal win against Taylor Fritz in straight sets earned him his sixth ATP final against fifth seed Roberto Bautista Agut.

[41] Starting his clay-court season seeded fourth at the Sardegna Open, Basilashvili reached the semifinals where he fell to defending champion and eventual finalist, Laslo Đere.

[50] Seeded third at the first edition of the Belgrade Open, he suffered a second round upset at the hands of qualifier Andrej Martin.

[52] Seeded fifth at the Stuttgart Open, his first grass-court tournament of the season, Basilashvili lost in the second round to eventual champion Marin Čilić.

[53] Getting past qualifying at the Halle Open, he reached the semifinals where he was defeated by fourth seed Andrey Rublev.

[56] Representing Georgia at the Summer Olympics, he lost in the third round to fourth seed and eventual gold medalist, Alexander Zverev.

[61] Basilashvili achieved his best result at a Masters 1000 in Indian Wells by reaching the final, beating Christopher Eubanks, Albert Ramos Viñolas, 24th seed Karen Khachanov, world no.

[69] Seeded fourth at the Open Sud de France, Basilashvili was eliminated in the second round by qualifier Damir Džumhur.

Seeded 15th, he retired during his first-round match against Grigor Dimitrov due to breathing issues and chest pain.

In the next three months, he further fell another 100 positions out of the top 200 following the 2023 Italian Open where he retired in the first round of qualifying, due to injury issues.

[102] On 15 October 2023, he came back to the ATP Challenger Tour at the 2023 Hamburg Ladies & Gents Cup, where he lost in the first round.

1086, at the 2024 Murcia Open, he reached his seventh Challenger final as a qualifier and moved 500 positions up in the rankings in the top 550 on 1 April 2024.