This study examines the impact of cash support from the Benazir Income Support Program (BISP) on willingness to pay for environmental services (WTPfES) among the ultra-poor in Pakistan using a quasi-experimental approach. We conduct empirical analysis using cross-sectional data of 1200 households by applying the regression discontinuity design (RDD) approach. The RDD-based empirical results show that BISP cash support positively impacts the willingness to pay for environmental services such as drinking water, sanitation, and waste disposal management services. The empirical analysis further depicts that cash assistance has a positive and significant impact on the willingness to participate in environmental services at the household and community levels. In addition, the additional income from the BISP helps families achieve better living standards and improve environmental services. The use of environmental services ultimately leads to better health among the target groups. The government may expand unconditional cash support to increase the use of quality environmental services.