The M114 was designed as a tracked reconnaissance and command vehicle, similar in shape but slightly smaller than contemporary US APCs like the M113, which it was intended to complement. Like the M113, the hull is built of all-welded aluminum, making it light enough to be airlifted as well as being air dropped by parachute. It was also fully amphibious, using its tracks as propulsion. Throughout its development, numerous configurations were used for its 12.7-mm M2 armament, which eventually gave way to a 20-mm M139 cannon. With the Vietnam War escalating soon after it entered, service, the conflict was used as a proving ground for the M114. Unfortunately it was found to have poor cross-country mobility, suffered from mechanical problems, was underpowered, and its lightened armor gave it little protection against mines. As a result, it was eventually phased out of combat units in the theater and replaced by assault variants of the M113. Nevertheless, it remained in US Army service in other theaters (including Europe) until finally retired by the end of the 1970s.

Development began in 1956 and resulted in the prototype T114 with a 7.62-mm machine gun. Production units were reclassified as the M114 and were followed by the M1142 that allowed the machine gun to be operated internally through a manually powered cupola. The M114A2 went further by adding a hydraulically powered cupola fitted with a 20-mm cannon based on the Hispano-Suiza HS.820.