Concrete is the primary building material worldwide with a substantial impact on the built environment sustainability. Hence, it is necessary to assess concrete’s combined functionality, economic and environmental impact. In this paper, two concrete sustainability assessment frameworks, MARS-SC and CONCRETop, were studied. Building on the identified gaps, a new framework, ECO2 was developed. ECO2 is a multi-criteria decision analysis framework that accounts for carbon sequestration of concrete, impact allocation of raw materials, and the impact from the use and end-of-life phases. Hence, it could be used to optimize the proportions of a concrete mix based on a user-defined sustainability objective. A case study concluded that, due to the whole life cycle scope, the environmental impact calculated through ECO2 is 20% higher than that by MARS-SC and CONCRETop. In case of reinforced concrete, where service life requirements are different, the ranking of the alternatives according to ECO2 will significantly change comparatively.