Hawaiian hoary bat is the only land mammal endemic to Hawaii and is listed as Endangered at both the state and federal levels. Hawaiian hoary bat is regularly included as a covered species in Habitat Conservation Plans developed for actions that may result in incidental “take” of the species; however, determination of recovery benefits has been challenging due to the paucity of information concerning threats, limiting factors, and ecology of the species. In collaboration with Hawaii’s Endangered Species Research Committee, we initiated a multi-year study in 2017 to investigate the overall distribution and seasonal occupancy of Hawaiian hoary bats on the Hawaiian island of O‘ahu. One of the primary objectives of the study was to investigate bat occupancy and distribution across O‘ahu. Data from acoustic bat detectors probabilistically distributed throughout the island and monitored year-round were used to assess bat distribution and seasonal occupancy over a five-year period. Bats were detected at 95% of detectors at least once during the study. However, activity rates were generally greater in the western and northwestern regions of the island. We present our findings on seasonal differences in bat distribution across O‘ahu and trends in occupancy estimated by season over the five-year study period.