The Piasecki HUP Retreiver was yet another of the company's line of tandem rotor helicopters, although due to its different fuselage shape did not get the "Flying Banana" nickname of other Piasecki designs. In contrast to its contemporary, the HRP which was designed for transport, the HUP was a dedicated utility helicopter designed for US Navy service, particularly on carriers and other large warships. Being a naval design, the HUP had folding blades although this was not required on carriers due to its compact fuselage. In order to be used for air-sea rescue, it also featured an electrically-operated door through which a rescue sling could be lowered. Other uses included as an anti-submarine platform (with dunking sonar) and it was eventually also adopted by the US Army with various structural improvements. However, they were seen as unsuitable for front line use and most were eventually handed back to the US Navy. Other users included Canada and it remained in service until the mid-1960s. Its design would serve as a precursor to the CH-46 and CH-47 (both by Boeing Vertol, which eventually purchased Piasecki in 1960).

The prototype XHJP-1 first flew in March 1948. Production units entered service with the US Navy as the HUP-1 which was later given an improved engine and designated HUP-2. An anti-submarine variant was known as the HUP-2S while a further utility variant was the HUP-3. The main Army version was the H-25A Army Mule which differed somewhat from naval types. After 1962, the HUP was renamed UH-25.