Born in August 1922, General Malhotra was commissioned into the Regiment of Artillery in November 1941. He commanded different Artillery Regiments between November 1950 and July 1961, besides being an instructor at the Defence Service Staff College , Wellington . He was the Military Attaché at the Indian Embassy in Moscow for over three years from June 1962.

He commanded an Artillery Brigade from August 1965 to January 1966 and there after took over a Mountain Brigade. He was promoted as Major General in September 1967 and commanded an Infantry Division for two years. He was posted as the Chief of Staff in a Corps Headquarters in the Eastern Sector in September 1969 till May 1972, when he took over a Corps in the Western Sector. In 1974, General Malhotra was appointed General Officer Commanding – in - chief Southern Command and in Jan 1977, he was appointed as the Vice Chief of the Army Staff. General OP Malhotra, assumed the office of the Chief of the Army Staff in June 1978.

After completing his three year tenure as the Chief of Army Staff, he was appointed as the Indian Ambassador to Indonesia in March 1982 and continued in that appointment for three years. In December 1990, he was appointed as the Governor of Punjab, a post he held till August 1991 when he resigned from this assignment. He was the President of the Equestrian Federation of India for nearly nine years. In 1994, the University of Jammu conferred the Degree of Doctor of Letters (Honours Causa) upon him.