This research highlights the essential role of civil infrastructure companies in advancing the United Nations Sustainable Development Goals (UN-SDGs). It emphasizes the need for integrated sustainability assessment at the project level and transparent reporting at the organizational level. To address current fragmentation, a two-step framework is proposed. The first step involves developing a correspondence matrix aligning project-level sustainability criteria with organizational-level Global Reporting Initiative (GRI) standards and relevant UN-SDG targets. The second introduces a composite index, the SDG Alignment Index (SAI), supported by two sub-indices: the Sustainability Coverage Index (SCI) and the Sustainability Disclosure Quality Index (SDQI). The framework was applied to 16 companies across Asia and Europe. Results indicate stronger social and economic sustainability reporting among European firms, while Asian firms show lower adherence to GRI-aligned disclosures. Notably, environmental sustainability reporting remains a challenge across both regions. The proposed approach provides construction companies, stakeholders, and policymakers with a practical tool for evaluating and improving sustainability performance, thereby enhancing alignment with the UN-SDGs.