<p>Hydrologic alterations of urban watersheds are commonly attributed to the collective impacts of urbanization and climate change. Watershed management and planning strategies focus on tools to mitigate flashy streamflows and reductions in groundwater recharge. This study aims to untangle the relative impacts of urbanization and climate variability on watershed hydrology and highlight implications for broader watershed and stormwater management. The focus is on 21 watersheds in the heavily urbanized Greater Toronto and Hamilton Area, a large urban region in Ontario, Canada, which has experienced rapid impervious area growth since the early 1990s. The majority of study watersheds experienced significant increases in urbanization over the study period. Select hydrologic signatures were computed for 1990–2022 and coupled with meteorological statistics and watershed-specific impervious cover data. This was done to distinguish climate and anthropogenic changes from the effects of watershed regulation on changes to watershed hydrology. Results show that several watersheds displayed statistically significant monotonic trends related to watershed baseflow, the coefficient of variation in daily streamflow, and watershed flashiness that more broadly correspond with changes in watershed imperviousness rather than meteorological conditions. Deviations in hydrologic signatures from typical trajectories associated with urbanization suggest other time-variant factors associated with urbanization (i.e., 1) implementation of groundwater protection policy, 2) installation stormwater control measures, and 3) recharge from leakage of the drinking water system) are important to consider for broader watershed management and planning.</p>