Donanma’nın Lockheed P2V “Neptune” ve Martin “P5M” Marlin’in değiştirilmesi için çalışmalar turboprop motorların hazır olmasından çok önce Lockheed tarafından donanmaya sunulmuştur. Bütün gereksinimleri karşıladığı için ihaleyi kazanıp Mayıs 1958’de ön araştırma ve geliştirme sözleşmesini yaptı. İlk prototip uçuşu da 19 Ağustos 1958’de gerçekleşmiştir.

Aynı uçağın elektronik savaş modeli olan EP-3B/C modeli de mevcuttur.

The turboprop-powered Electra airliner from which this superb ASW aircraft was derived had initially experienced major structural and powerplant difficulties. Quickly rendered obsolete in the eyes of travelers by the introduction of pure-jet transports, it remained in production for only four years and was rapidly withdrawn from use by most major carriers. Fortunately for Lockheed, the Electra’s technical difficulties were easily resolved and, unlike airliners, the US Navy and several foreign air forces found considerable merits in turboprops, as the ASW and maritime patrol missions for which the Orion was derived from the Electra favored long loitering capabilities over higher cruise speed.

Development of the Electra to provide the Navy with replacements for its land-based Lockheed P2V Neptunes and Martin P5M Marlins was initiated in 1957, before the first flight of the turboprop-powered airliner, when Lockheed submitted a formal proposal . With its design meeting fully the requirements of the Navy, Lockheed easily won the design competition, was awarded an initial research and development contract in May 1958, and first flew the Orion’s aerodynamic prototype on 19 August 1958.

The “orion” also has the EP-3B/C electronic counter -measure variant.