Urbanization in Northern Nigeria has resulted in the proliferation of modern architectural typologies that often overlook the region's environmental conditions and cultural traditions. This study investigates the integration of vernacular architectural wisdom into climate-resilient urban development, focusing on Sokoto, Katsina, and Kano as case study cities. The study employed a mixed-methods approach, including field measurements, structured interviews, simulation analysis, and policy review, to assess the thermal performance, spatial configuration, and material sustainability of vernacular and modern buildings. The results show that traditional Hausa architecture achieves a mean indoor temperature drop of 4-6°C relative to outdoor ambient conditions, principally due to its courtyard orientation, thick earthen walls, and passive ventilation systems. Comparative life-cycle assessments reveal that vernacular materials possess 60-75% less embodied energy than modern counterparts. The findings further show that residents link vernacular dwellings with cultural identity, comfort, and ecological balance. However, current urban policies remain fragmented, and there are no frameworks that encourage passive design and indigenous material use. This paper proposes an integrative model combining passive-vernacular and modern technologies with educational and policy interventions. Finally, the study demonstrates that incorporating vernacular principles into Nigeria's urban design codes can improve environmental management, cultural continuity, and resistance to climate change, all of which are consistent with the United Nations Sustainable Development Goals (SDGs 11 and 13).