He is best known for his clay court game, kick serve and strong flowing groundstrokes, especially his one-handed backhand.
His first appearance in the main draw of a grand slam was at Australian Open and he reached second round where he lost to Kei Nishikori.
He bettered this at the French Open by reaching the fourth round where he was beaten in straight sets by then-world number one and eventual champion Rafael Nadal.
20 Benoît Paire in the second round, that was his first tour-level semifinal appearance after losing all eight prior quarterfinals matches before in his career.
In Indian wells, the Serbian defeated five opponents to reach the fourth round eventually losing to Pablo Carreño Busta.
His contributions in successful Davis Cup ties against Russia & Spain, resulted in Serbia making the semifinal where he defeated Lucas Pouille but lost to Jo-Wilfried Tsonga.
His next match was a five set loss to Miami Masters champion John Isner in a Davis Cup tie.
A temporary return to the Challenger Tour resulted in winning the Open Region Guadeloupe.
After qualifying for the Monte-Carlo Masters, he faced 12 time Grand Slam champion Novak Djokovic, losing in straight sets.
At the Madrid Masters, he defeated former top ten player Richard Gasquet in the second round, followed by a victory over world No.
En route to the final, Lajović defeated former top 10 player David Goffin, reigning French Open finalist, world No.
Lajović won his first ATP Tour singles title at the Croatian Open in Umag, defeating Hungarian Attila Balázs in straight sets in the final.
At the Australian Open he defeated 2018 semifinalist Kyle Edmund in straight sets before losing to world no.
[9] Seeded 23rd at the Australian Open, he reached the fourth round of a Grand Slam for a second time in his career.
[10] Seeded third at the Open Sud de France in Montpellier, Lajović was eliminated in the second round by Dennis Novak.
He ended up losing to Casper Ruud, Cristian Garín via retirement, and Roberto Bautista Agut.
[15][16][17] Serbia ended up third in Group A. Seeded sixth at the Sydney Classic, he was defeated in the second round by American Maxime Cressy.
[30] Seeded second at the Emilia-Romagna Open, an ATP Challenger event in Italy, Lajović reached the semifinals where he lost to Borna Ćorić.
[35] In January, Lajovic lost in three tight sets in the qualifying of ASB Classic to Christopher Eubanks.
[36] In the second round, he defeated Camilo Ugo Carabelli in straight sets to reach his first quarterfinal of the season.
[38] At the Rio Open, Lajovic reached his second quarterfinal after defeating fifth seed Diego Schwartzman in the first round and compatriot Laslo Djere in the second, both in straight sets.
Next he defeated 30th seed Maxime Cressy to reach the third round, where he lost to Carlos Alcaraz in straight sets.
[46] In the semifinals, he won over fourth seed and compatriot Miomir Kecmanović in three sets, after three hours of play.
[49] In the second round Lajović scored his third Top 10 win in the space of nine days by taking out seventh seed Félix Auger-Aliassime.
[50] In September, during the Davis Cup Finals in Valencia, Lajovic, playing singles, won in straight sets against Hong Seong-chan from South Korea and gave the all important first point to his Serbian Davis Cup team.
[53] in the same month, he also made the second round at the next Masters in Paris as a lucky loser, defeating wildcard Benjamin Bonzi.
At the 2024 Argentina Open he reached back-to-back quarterfinals at this tournament defeating eight seed Arthur Fils and Alejandro Tabilo before losing to eventual champion, wildcard Facundo Diaz Acosta.