This study constitutes the first quantitative assessment of winter use of the northern Strait of Georgia by killer whales, which presents a substantial contribution to the limited knowledge of killer whale habitat use in British Columbia during the winter. Passive acoustic monitoring revealed extensive use of this area by three sympatric killer whale populations from November to April over three seasons. This study also evaluated the effect of using multiple simultaneous acoustic recorders to characterize killer whale habitat use, and developed a data-driven approach to define acoustic residency time.