This study examines the relationship between urban planning decisions and heat vulnerability in Lahore, Pakistan, focusing on two contrasting areas: the high-density Jail Road district and the peripheral Airport area. Through a mixed-methods approach combining geospatial analysis, temperature monitoring, and ethnographic research conducted between March-August 2023, the study reveals significant temperature differentials (3.2°C ± 0.5°C) between the two areas, strongly correlated with building density (r² = 0.82). The research identifies marked disparities in adaptive capacity, with only 45% of Jail Road residents having access to air conditioning compared to 72% in the Airport area. Analysis of health impacts, energy consumption, and socioeconomic factors demonstrates how urban planning decisions intersect with social vulnerability to create compound heat risks. The findings emphasize the need for heat-sensitive urban planning policies and targeted interventions for vulnerable communities, contributing to broader discussions on climate justice and sustainable urban development in the Global South.