The reproductive phenology of tropical geckos varies considerably between species. We investigated the reproductive timing of Phelsuma inexpectata, a critically endangered tropical squamate endemic to Reunion Island (western Indian Ocean). From February 2018 to August 2020 (30 months), we carried out monthly monitoring of laying sites. Phelsuma inexpectata exhibited a seasonal reproductive pattern, with breeding activity from the end of the austral winter to the end of the austral summer. We observed intra-and interannual synchronicity of oviposition in September. The seasonal reproductive pattern appears to be synchronized with optimal environmental conditions (temperatures, food resources) for the survival of eggs and hatchlings. Females deposited their eggs in communal laying sites (up to 9 eggs) and exhibited interannual laying site fidelity (50% of the laying sites were reused in the second breeding season). Minimum and maximum incubation periods (± SD) were 69 ± 24 days and 115 ± 25 days, respectively. Our study provides the first description of the Manapany Day Gecko reproduction in the wild and highlights for the first time the very high synchronicity of oviposition in the genus Phelsuma. These results will be very useful to improve the conservation of this species, in particular with regard to the timing of predator control, designing monitoring protocols for breeding and survival parameters, and implementing a captive rearing program for hatchlings.