After becoming adopted as a primary trainer by the USAF, the United States Navy and Marine Corps adopted it as well. Although the Air Force phased out the aircraft from primary pilot training by the early 1960s, continuing use only for limited training of special operations aircrews and for primary training of select foreign military personnel, the aircraft continued to be used as a primary trainer by the Navy (and by default, the Marine Corps and Coast Guard) well into the early 1980s.
The largest single concentration of this aircraft was employed by the U.S. Navy at NAS Whiting Field in Milton, Florida, in the training of student naval aviators. The T-28's service career in the U.S. military ended with the completion of the phase-in of the T-34C turboprop trainer. The last U.S. Navy training squadron to fly the T-28 was VT-27, based at NAS Corpus Christi, Texas, flying the last T-28 training flight in early 1984. The last T-28 in the Training Command, BuNo 137796, departed for Naval District Washington on 14 March 1984 to be displayed permanently at Naval Support Facility Anacostia, D.C. Many T-28s were subsequently sold to private civil operators, and due to their reasonable operating costs are often found flying as warbirds today.
In September 2011, a T-28 Trojan stunt team lost one of its aircraft and crew during an air show in Martinsburg, West Virginia. No other casualties were reported.
In 1963, a Royal Lao Air Force T-28 piloted by Lieutenant Chert Saibory, a Thai national, defected to North Vietnam. Saibory was immediately imprisoned and his aircraft was impounded. Within six months the T-28 was refurbished and commissioned into the North Vietnamese Air Force as its first fighter aircraft.
T-28s were supplied to the South Vietnamese Air Force in support of ARVN ground operations, seeing extensive service during the Vietnam War in VNAF hands, as well as the Secret War in Laos. A T-28 Trojan was the first US fixed wing attack aircraft (non-transport type) lost in South Vietnam, during the Vietnam War. Capt. Robert L. Simpson, USAF, Detachment 2A, lst Air Commando Group, and Lt. Hoa, SVNAF, were shot down by ground fire on August 28, 1962 while flying close air support. Neither crewman survived. The USAF lost 23 T-28s to all causes during the war, with the last two losses occurring in 1968.
T-28s were also used by the CIA in the former Belgian Congo during the 1960s.France used locally re-manufactured Trojans for close support missions in Algeria. The Philippines utilized T-28s (colloquially known as "Tora-toras") during the 1989 Philippine coup attempt, the aircraft were often deployed as dive bombers by rebel forces.
AeroVironment has modified and armored a T-28A to fly weather research for South Dakota School of Mines & Technology, funded by the National Science Foundation.