Brigadier General Sultan Khalid Mahmud joined Pakistan Army as a Gentleman Cadet in 1972 at Pakistan Military Academy, Kakul, Abbottabad. The Brigadier General was born on 26th March 1954 in Rawalpindi. His father was a bureaucrat serving with the then President Field Marshal Muhammad Ayub Khan.
The Brigadier General started his career in the Pakistan Army by joining the Pakistan Army Corps of Artillery as a Gunner. His parent unit was 47 Field Artillery Regiment. As a Second Lieutenant who graduated from the Pakistan Military Academy in the 50th Long Course was posted on an assignment in the District of Mansehra as a Chief Martial Law administrator of the region. After his successful completion of the assignment, he was promoted to the rank of Lieutenant because of his which he posted to Balochistan to carry out operations against the unlawful groups. Then, he was promoted to the rank of Captain and he went on to the School of Artillery in Nowshera to complete his Young Officer's Course. Once the course was completed he became the Adjutant of his parent unit 47 Field Artillery Regiment. After the completion of his assignment as an Adjutant, he was posted in Karachi, where he attended an Arabic Language Course because he was selected to be posted in Saudi Arabia to protect the Two Holy Mosques as well as to train the Kingdom of Saudi Arabian Armed Forces. He was promoted to the rank of Major as a result.
He came back after two years and then he became a Principal Staff Officer to Commandant of Command & Staff College Maj General Burki. He remained as General's PSO for two years and after successful completion of his term and He went on to join the Command & Staff College as an Officer Student. He completed the course with distinction due to which he was posted as 2nd in Command of 49th Field Artillery Regiment. After that, he remained with the unit in Sialkot. He was then posted to become General Staff Officer (GSO-1) to the then Major General Pervez Musharraf in Okara. Due to his outstanding performance, he was promoted to the rank of Lieutenant Colonel and was selected to command his parent unit. As a commanding officer of the 47 Field Regiment for 2 years, the unit performed very well due to which they were tasked to defend Pakistan's borders at Siachin. After the completion of his term as Commanding Officer, he was transferred to command his second parent unit, 49 Field Artillery Regiment due to his outstanding services at Siachin for 6 months. Then he was selected to represent Pakistan by attending Jordanian Command & Staff College. Where his performance as a student was top notch due to which King Hussain gave the title of "Sultan" to Lieutenant Colonel Khalid Mahmud. Eventually, Sultan became part of his name as it was such a matter of pride and honor.
After completion of his course in Jordan, the Lieutenant Colonel was transferred to the General Headquarters in the MT Directorate, where he went to represent the Pakistan Army in the United Kingdom and the United States of America. After the completion of his assignment at GHQ, he was promoted to the rank of Full Colonel and he was posted as a Colonel Staff to the 37th Infantry Division in Gujranwala, where he assisted the General Officer Commanding (GOC) to perform their duties effectively and efficiently. He assisted two General in his true, Lieutenant General Tariq Waseem Ghazi and Lieutenant General Javed Alam. On the recommendation of the then Major General Javed Alam, the Colonel was promoted to the rank of Brigadier General and he was posted as 37 Division Artillery as its Commander. As it was the era of another Martial Law, he was made the Chief Martial Administrator of Faisalabad Division. Where the district administration and the district government was under the Brigadier General. He led the restructuring of the Faisalabad Division by enforcing law and order and ensuring political stability and economic development. After his assignment was completed in 2001 due to his meritorious services he was assigned to another mission by awarding him to become a Garrison Commander at Dera Ismail Khan where he commanded the 5 Independent Artillery Brigade which is basically the size of a Division Level Brigade. The brigade also had the privilege to be part of Army Strategic Forces Command as it had active assets part of it.
In the 2001 escalation, the Brigadier General was given an additional task to lead the Pakistan Rangers Sindh on the battlefield as he was made the Acting Director of General Pakistan Rangers Sindh. He led the troops at the Rahimyar Khan front and made sure the Indian Army couldn't penetrate the region. Since the Brigadier General outperformed over here as well he was transferred to further increase his skills at the National Defence University, Islamabad to study Master of Strategic Studies. After that, he was appointed as the Assistant Chief of Logistics Staff (ACLS) at the Chief of Logistics Staff Secretariat in the General Headquarters Rawalpindi. After that, he was made the Commander of Logistic Areas, Balochistan as it was a post of Major General but due to Brigadier General Sultan Khalid's outstanding services, he was appointed as a Commander of Logistic Areas of Balochistan for 2 years.
On completion of his tasks at Quetta, he was made Director-General of the National Accountability Bureau, Rawalpindi, and was promoted to the BPS 21. In 2007, he resigned from the Pakistan Army and the Government of Pakistan as he wanted to end his services on a good note.