Accelerated climate warming in northern Canada is driving substantial changes in air temperature, precipitation regimes, permafrost stability, and wildfire frequency and severity. These factors have been individually linked to increases in discharge across permafrost regions, yet their relative contributions and cumulative hydrological impacts remain poorly constrained. This study investigates the individual and cumulative influences of climate change, permafrost thaw, and wildfire disturbance on streamflow variability in La Martre River watershed (14,500 km^2), central Northwest Territories, which has experienced marked increases in discharge since 1976. The Raven hydrological modeling framework was applied to simulate watershed responses during the recent past (1976–2000), present (2001–2025), and future (2026–2050) under a high-emissions scenario (RCP 8.5). Model parameterization incorporated observations from burned and unburned field sites to represent climate- and disturbance-driven changes in hydrological processes, including active layer dynamics, peat plateau–wetland connectivity, and land cover change. Results show that increased precipitation is the dominant driver of streamflow change, producing an upward shift in the hydrograph across seasons. Permafrost thaw further enhanced discharge, though secondary to precipitation. Wildfire had a modest direct hydrological impact but accelerated permafrost degradation, indirectly amplifying streamflow responses. The cumulative impact of climate change, permafrost thaw, and wildfire produced increases in annual, winter, and peak discharge exceeding those associated with any single driver. Projections indicate these trends will persist under future climate conditions. These findings highlight the sensitivity of northern watersheds to interacting climate, permafrost, and disturbance processes, with implications for water resources and ecosystem function in (sub-)Arctic regions.