Land snails of the genus Poecilozonites, endemic to Bermuda, have undergone precipitous declines, and both extant species, P. bermudensis and P. circumfirmatus, are categorized as Critically Endangered on the IUCN Red List. Here we report on recovery efforts to reintroduce P. bermudensis derived from a remnant wild population and ex situ breeding programme to within the species’ indigenous range. Follow-up monitoring of initial reintroductions on the small Nonsuch Island carried out over 7 years revealed that the snails rapidly established a self-sustaining population at one of three release sites. By 2023, the snails, released in 2016, had increased their area of occupancy to 6,849 m2, moved up to 92 m from the release site, and reached an estimated mean density of up to 44.2 adult snails/m2. Across the archipelago, we released 105,970 P. bermudensis (adults and juveniles) to 11 offshore islands and 16 main island sites from 2019 to 2022. Based on persistence, reproduction, and expansion from the release site after at least 1 year from release, reintroductions to six offshore islands were successful, but those on the main island failed, possibly because of higher predation pressure and paucity of suitable refuges. Controlling predators, such as rodents, and safeguarding these offshore islands against predator incursion is essential to ensure continued survival of the reintroduced populations.