Born in Manipur, Singh began his career in his home state with Birchandra Memorial Sporting Club.

[3] In 2018, it was announced that Naorem had signed for the Indian Super League club Kerala Blasters from Shillong Lajong F.C.

[12] He scored his first goal of the 2023 Indian Super League against Bengaluru on 3 October in a 2–1 defeat away at the Sree Kanteerava Stadium.

[14] Mahesh won the 2024 Indian Super Cup with East Bengal, having returned from the national team in time for the final of the tournament, and provide an assist for Nandhakumar Sekar as East Bengal won 3–2 against Odisha to end a twelve year wait for a major domestic trophy for the club.

[15] On 14 March 2023, Singh was named amongst the eleven reserves for Indian senior squad for upcoming Hero Tri-Nation International Football Tournament.

[16] Five days later, he was called up to the Indian senior camp for the first time, in place of Sivasakthi Narayanan, who withdrew through an injury.