The Black-capped Petrel Pterodroma hasitata is a pelagic seabird with a dangerously small population size. Remaining breeding sites are threatened by habitat loss, introduced predators, and direct harvesting. The species likely also faces several threats at sea, but because knowledge of its distribution range and ecology is meagre at best, it is challenging to take concerted action to improve its conservation status. The species is currently known to breed only on Hispaniola (in the northern Caribbean Sea), but most at-sea observations are from the Florida Current and the Gulf Stream off the southeastern coast of the USA. Within the Caribbean Sea, observations are scarce. We compiled a database of at-sea sightings of Black-capped Petrels in the Caribbean Sea from 1953 to 2018 by thoroughly reviewing published and unpublished records (Appendix 1); here, we add to the literature 12 new records from a research cruise conducted in February 2018 across the Caribbean Sea. Our database was augmented with recently published information from three birds that were fitted with tracking devices. Based on the collected information, we argue that the existing distribution maps of Black-capped Petrels need adjustments. We show that Black-capped Petrels have been recorded throughout the central parts of the Caribbean, from the known breeding sites in the north down to coastal waters off Panama, Colombia, and Venezuela. However, the birds probably forage only in small parts of the Caribbean Sea (i.e., the coastal upwelling zones off Hispaniola and Cuba in the north and off the South American mainland in the south). The waters in between (i.e., in the central Caribbean Sea) appear to be mainly used as a corridor, while the eastern and western parts are unimportant. This indicates that certain hotspots within the Caribbean Sea may be more important to this endangered species than previously thought.