Known for his work in the Punjabi film industry, Mahabir Singh was first seen in the 2012 sports drama Kabaddi Once Again. Mainly seen playing supporting roles, Mahabir has other movies such as Qissa: The Tale of a Lonely Ghost, Ronde Sare Vyah Picho, Yoddha: The Warrior, and Mango Dreams to his credit. In 2017, the actor featured alongside Harp Farmer in the thriller Kawela, where he played the role of Inspector Gurjinder Singh. Next, he was seen in the 2017 sports action drama Rocky Mental, which featured Parmish Verma, Tannu Kaur Gill, and Kanika Maan in pivotal roles. His other releases include Kirdar-E-Sardaar (2017), Daani Paani (2018) and Soorma (2018). His 2019 releases include Nadhoo Khan and Amaanat.