Randolph AFB is one of the oldest fields in the US Air Force, and one of the earliest and most carefully planned of all air bases from before the Cold War. In 1926, with the conversion of the US Army Air Service to the US Army Air Corps; the Air Corps Act provided for the expansion of the Air Corps, with purchase of new aircraft, ground facilities, and an increase of personnel.

In assessing the needs of the Air Corps, General Frank P. Lahm, "the nation's first military aviator," in charge of flying training for the Air Corps, recognized that the centers of Air Corps training, Kelly Field and Brooks Field, were too small for projected personnel increases, poor repair, and lacked adequate housing, hangar space, fuel facilities, and had other design flaws. The general appointed a committee of five officers to plan a new airfield; this committee was presented with unsolicited initial plans by 1st Lt. Harold Clark, a motor pool officer with pre-military career training as an architect, for a radical and futuristic airfield using concentric circular design with quadrant sections, between two runways aligned with prevailing winds. Gen. Lahm was impressed and reassigned Lt. Clark to finalize his design. This was done in 1927, and a site was scouted and selected. The new field was named for Captain William Millican Randolph, who had been on the name selection committee when killed in a crash in 1928. Additional plan design changes were ongoing, but construction began in November 1927, and continued through 1931, with dedication in 1930. 1931 saw the relocation of the Air Corps Training Center, School of Aviation Medicine, and various other flying schools to Randolph, and the Primary Flying School opened at Randolph in November 1931. Randolph Field had become the "West Point of the Air."

Randolph Field trained thousands of pilots through basic and primary flight training in the 1930s, with increasing numbers as the global political situation of the decade became more tense. At that time law required that 90% of the commissioned officers of the Air Corps be rated pilots, and so nearly all officers of the time went through Randolph for training at least. The training demands of the later 1930s were so great the Air Corps contracted primary training to civilian instructors, leaving basic to the Randolph school.

In 1935 Randolph Field was the setting and shooting location for the Hollywood film West Point of the Air, starring Wallace Beery, with Robert Young, Lewis Stone, Maureen O'Sullivan, Rosalind Russell, and Robert Taylor, all stars of their era.

In June 1941 the Army Air Corps became the Air Forces, and in December the USA was plunged into World War Two. Randolph Field trained pilots as fast as practical, with specialized pilot training conducted at many other fields and bases around the country. In 1943 Randolph instituted the Central Instructor's School, and trained over 15,000 instructors before the end of the war. The CIS was briefly transferred away from Randolph in 1946.

The post-War and Cold War saw a series of training transfers through Randolph, including Combat Crew Training, Helicopter Training, and instrument training. Recently, Randolph AFB has been the central aviation training center for instructor training and refreshing/recurrency, navigator and combat systems officer training (CSO training since transferred out), and has supported Marine and Navy aerial navigation training. Electronic Warfare Officer training was added to Randolph's portfolio in the post BRAC Air Force. In 2010 Randolph AFB was joined with principal basic USAF training center Lackland AFB and Fort Sam Houston, the US Army's principal medical training center, to form Joint Base San Antonio. Recent years have also seen upgrading of housing, the base exchange, and repaving of principal entrance Harmon Drive.