This study analyzes the causal relationship between external institutional pressures and the substantive adoption of sustainability practices within the electronics manufacturing sector in CALABARZON, Philippines. As a premier industrial hub, the region faces a critical transition toward a circular economy following the enactment of the EPR Act of 2022. Grounded in Institutional Theory, the research evaluates how coercive, normative, and mimetic pressures influence the integrated Triple Bottom Line (TBL) performance comprising environmental, social, and economic dimensions. Utilizing a descriptive-causal research design, data were collected from 102 electronics manufacturing employees via purposive sampling. Multiple linear regression analysis revealed that the three institutional pressures explain a staggering 92.5% of the variance in sustainability adoption. Coercive pressure emerged as the most significant predictor, driven by strict regulatory mandates from PEZA and the DENR, as well as global buyer requirements. Normative pressure follows, reflecting the professionalization of environmental stewardship through industry networks like SEIPI. Mimetic pressure, while significant, holds the lowest impact. The findings underscore the sector's commitment to SDG 9 (Industry, Innovation, and Infrastructure) through the integration of green manufacturing and SDG 12 (Responsible Consumption and Production) via robust hazardous waste management and material recovery. The study concludes that the institutional environment is an exhaustive predictor of corporate sustainability, proposing a framework to align regulatory compliance with long-term regional competitiveness.