Rajesh was born in Jalandhar, Punjab on 12 March 1971 as the eldest son of Balakrishnan Nair and M. K. Remani.

Rajesh is married to Ninitha Kanicheri, who is an assistant professor at Sree Sankaracharya University of Sanskrit.

He also held positions including the Joint Secretary and Vice President of SFI Central Committee.

M B Rajesh is the current lawmaker from Thrithala legislative constituency in Palakkad district.

The appointment of his wife as assistant professor in Kalady Sanskrit university snowballed into a major political controversy ahead of 2021 legislative assembly elections as one of the subject experts in the interview board alleged irregularities in the process.