His father Gopal Singh Khalsa belongs to Ramdasia Sikh who was an Akali Dal politician and served as the Chief Parliament Secretary of Punjab assembly in 1937, and was elected to the Punjab Legislative Assembly in 1952, serving as the leader of opposition.
During his academic career (1964-1974), he published two textbooks: A Manual of General English and Social Science.
[4] During 1990-91, he served as the Chairman of Punjab Human Rights Organization, an NGO that highlighted the excesses committed by the state government during the anti-insurgency operations.
[5] Harinder Singh joined Shiromani Akali Dal, and was elected as an MP from Bhatinda in 1996, winning by a margin of 92,229 votes.
[6] In 2014, Harinder Singh joined the Aam Aadmi Party, and contested the 2014 Lok Sabha elections from Fatehgarh Sahib.