Partnering with compatriot Vishnu Vardhan, the pair lost the final to team of Laurynas Grigelis and Zdeněk Kolář.

He won his first ATP Challenger singles title at the Kunming Open by defeating Mohamed Safwat in the final.

[9] In an all-Indian final, he defeated Saketh Myneni at Bengaluru Open to lift his second Challenger singles trophy.

Although he was chosen as lucky loser after Nick Kyrgios withdrew from the competition, Gunneswaran could not participate in the main draw event as he had already left Paris before Kyrgios announced his withdrawal, thus failing to debut in the main draw of a Grand Slam event.

[12] In August, he won the bronze medal in the men's singles tennis event at the 2018 Asian Games in Jakarta.

[14] At the Australian Open, he won the qualifying competition and debuted in the main draw of a Grand Slam event.

[16] Gunneswaran came through the qualifying of the 2019 BNP Paribas Open and defeated Frenchman Benoit Paire in straight sets to enter the second round.

[17] Gunneswaran's run at the Indian Wells Masters came to an end following a straight set defeat to Ivo Karlovic in the third round.

[19] In July his ranking automatically enabled him entry to the main draw at Wimbledon, where he lost in the first round to Milos Raonic.