After graduating from high school, he entered active military service in November 1942 as an aviation cadet in the United States Army Air Forces, and received his pilot wings and commission as a second lieutenant in February 1944.
White was recalled to active duty in May 1951 for the Korean War, where he served as a pilot and engineering officer with the 514th Troop Carrier Wing at Mitchel Air Force Base.
He made his first test flight of the X-15 on April 15, 1960, when the aircraft was fitted with two interim, 16,000 lbf (71 kN) XLR-11 thrust rocket engines.
On November 9, 1961, White flew the X-15 at 4,093 mph (6,587 km/h), making him the first pilot to fly a winged craft at six times the speed of sound (Mach 6).
President John F. Kennedy used the occasion to confer the most prestigious award in American aviation, the Robert J. Collier Trophy, jointly to White and three of his fellow X-15 pilots: NASA's Joseph A. Walker, Commander Forrest S. Petersen of the U.S. Navy, and North American Aviation test pilot Scott Crossfield.
A day later, Air Force Chief of Staff General Curtis E. LeMay awarded White his new rating as a Command Pilot Astronaut.
Major Bob White was featured with a cover story in the August 3, 1962, issue of Life magazine, detailing his July 17 flight.
He flew 70 combat missions over North Vietnam, including leading an attack against the Paul Doumer Bridge in Hanoi on August 11, 1967, for which he was awarded the Air Force Cross.
During his tenure, testing was begun on such important programs as the F-15 Air Superiority Fighter, the A-X ground attack aircraft, and the Airborne Warning and Control System.
Other achievements The President of the United States of America, authorized by Title 10, Section 8742, United States Code, awards the Air Force Cross to Colonel Robert M. White, for extraordinary heroism in military operations against an opposing armed force as an F-105 Mission Commander near Hanoi, North Vietnam, on 11 August 1967.
On that date, Colonel White led the entire combat force against a key railroad and highway bridge in the vicinity of Hanoi.