Fisheries bycatch represents a significant threat to cetaceans worldwide. To mitigate the unintentional capture of cetaceans, understanding the spatiotemporal patterns of cetacean bycatch is essential. In this study, Western and Central Pacific Ocean (WCPO) longline fishery cetacean bycatch data from 2013 to 2019 was analyzed using Bayesian Hierarchical Models (BHMs). The overall average bycatch per unit effort (BPUE) across the study area was 0.0129 bycatch per thousand hooks. Inter-annual variation in BPUE was little and potentially linked with climatic events. The BPUE was highest for sea surface temperatures of 20 degrees C and 30 degrees C that are known to be the most suitable temperatures for various cetacean species and tuna species Furthermore, the BPUE was positively linked with the chlorophyll-a concentration, which may be explained by the strong association between chlorophyll-a concentration and fish density. Three spatial hotspots where longline fishery bycatch events are most frequent were identified in the WCPO that should be taken into consideration when implementing bycatch mitigation strategies. Reducing the intensity of fishing activities in these hotspots could be attempted to decrease longline fishery cetacean bycatch incidents. Nonetheless, further data collection and analysis are required to explore seasonal fluctuations, which will aid in the development of suitable mitigation strategies.