In 2020, the White’s seahorse Hippocampus whitei was listed as an Endangered species on Australian state and federal legislation. Its threatened species status resulted from decline populations across its range which are attributed to habitat loss over the past decade. To help recover declining populations, conservation stocking has been proposed as a possible management tool for species recovery, however, the viability of such a reintroduction program for seahorses has not been assessed to date. This study implemented a pilot conservation stocking program using adult H. whitei from Sydney Harbour, Australia, as brood stock. Captive-bred juvenile seahorses (~6 months old) were released back into Sydney Harbour on two different artificial habitat types: “seahorse hotels” and protective swimming net. To assess the survival and behaviour of the seahorses, a monitoring program was implemented involving underwater visual census surveys of the tagged seahorses. The numbers of captive-bred seahorses were found to gradually decline over 12 months; however, several animals were still recorded on the site two years after release and 9 individuals were found to be sexually reproducing. Seahorse abundance was found to be higher on the seahorse hotels than the swimming net, with resightability and habitat persistence estimates higher for those individuals released onto the hotels. This study demonstrates that captive-bred seahorses can survive in the wild and contribute to local seahorse population recovery through increased abundance and reproductive success.