Megaprojects are expected to generate long-term value for society while advancing economic and technological goals. However, their governance still prioritizes cost, time, and scope over social and environmental performance. This paper investigates the barriers that prevent project managers and organizations from effectively integrating social and environmental impact into megaproject governance. Drawing on a qualitative approach based on a narrative and critical literature review, complemented by secondary case evidence, the study identifies four interrelated levels of barriers: project manager, organizational, stakeholder, and institutional. The findings show that these barriers are not isolated challenges but expressions of a broader governance misalignment between public and private actors. Short-term incentives, fragmented accountability, and weak regulatory coherence hinder the alignment of sustainability objectives across governance levels. The paper argues that overcoming these barriers requires reframing social and environmental integration as a process of value co-creation, supported by empowered project managers, adaptive organizations, and coherent institutional frameworks. By exposing the systemic nature of the problem, this study contributes to the understanding of how megaproject governance can evolve towards more responsible, collaborative, and sustainable forms of value creation.