Tuanku Salehuddin's military career started when he underwent cadet training at the Indian Military Academy in Dehradun from July 23, 1962 to June 30, 1963. He was appointed Junior Lieutetant on October 23, 1963. On February 12, 1964, he was commissioned as a lieutenant and stationed with the 2nd Battalion of the Royal Malay Regiment in Pengkalan Chepa, Kota Bharu, Kelantan.