Invasive Barred Owls (Strix varia; BO) have become the dominant threat to Northern Spotted Owls (Strix occidentalis caurina; NSO), yet the mechanisms driving this threat remain unclear. We used GPS telemetry to quantify BO space use relative to mapped NSO habitat across northwestern California in areas with concurrent BO removals. We tracked 55 BOs and estimated mean home ranges of 6.7 km². Resource selection functions showed that BOs used NSO habitat 1.38× more intensively than non-habitat, with selection increasing monotonically across NSO nesting and roosting (N/R) suitability classes and peaking 1.50× higher in the highest-quality N/R forest. On average, 71% of each BO home range overlapped mapped NSO habitat, and 39% overlapped highly suitable N/R forest. Each BO home range encompassed an average of 4.2 km² of NSO habitat, indicating that removals can directly restore functionally available habitat. Across 619 male BO removals in our project, this equates to ~2,600 km² (~141 NSO pairs) of potential NSO habitat recovered. Spatial projections revealed the strongest BO selection in northern and coastal portions of California, identifying priority areas for BO management. Our findings demonstrate that BOs disproportionately occupy forests most valuable to NSOs and that removals can yield quantifiable conservation gains.