Majithia was commissioned a pilot officer in the flying branch of the Indian Air Force Volunteer Reserve on 8 November 1939, two months after the start of the Second World War.[6] He rose to command a fighter squadron until he left the Air Force in 1944 to pursue a political career.[7] From 1945 to 1947, he was member of Central Legislative Assembly, served on the Defence Consultative Committee and was principal of Khalsa College, Amritsar.[7] After independence in 1947, he was promoted to honorary wing commander in the (Royal) Indian Air Force and appointed ambassador to the neighbouring country of Nepal, where he remained until 1949.
^Rekhi, Gurnam Singh (1999). Sir Sundar Singh Majithia and His Relevance in Sikh Politics(PDF). Har-Anand Publications Pvt. Ltd. p. 15. ...the small village of Majithia (near Amritsar)—which the family of Sir Sundar Singh, of Shergill clan among the Jat Sikhs—had adopted as their surname, could also be proud of its illustrious Sardars.
^The Indian Journal of Political Science. India, Indian Political Science Association, 1974.
^Indian Air Force - Air Force List. HM Stationery Office. 1941. pp. 1192–1199.