He once told an interviewer that his father was an atheist and a follower of the veteran social reformer Sahodaran Ayyappan, who was also from North Paravur, and so named his son Salim Kumar to avoid religious associations.

Boys High School, North Paravur; and completed his pre-degree education at Sree Narayana Mangalam College Malyankara, Moothakunnam.

Before entering into Malayalam film industry, Salim Kumar was chosen as host for a comedy programme called Comicola broadcast on Asianet.

He made his debut in Malayalam cinema with the 1997 family drama Ishtamanu Nooru Vattam, directed by Siddique Shameer.

After getting impressed with his performance in Satyameva Jayathe, director Rafi Meccartin offered Salim a role in his movie Thenkasipattanam, which was a major breakthrough in his film career.

In the movie Kalyanaraman, Salim Kumar played the role of Pyaari, which is considered one of the finest comedy performance in his career.

[8] He played one of the lead roles in the 2002 slapstick comedy film Bamboo Boys alongside Kalabhavan Mani, Cochin Haneefa and Harishree Ashokan.

The many expressions of Manavalan, including his helpless face, his coy smile and act as a rich man smoking pipe later developed a cult following in Kerala troll community and are widely used in memes.

[10][11] Alongside Jayasurya, Salim Kumar's other famous role is Dance Master Vikram in the movie Chathikkatha Chandu (2004).

[13] Some of his other popular roles were Raajakkannu in Thommanum Makkalum, Umakandan in Pandippada, Chidhambaram in Hallo, Naranimangalam Narayanan in Romeo, Inspector Shyamalan in Annan Thampi and Maakri Gopalan in Chattambinaadu.

Salim Kumar appeared in a hip-hop number in Vineeth Srinivasan's album "Coffee @ MG Road - Palavattam" (2008).