Despite the fact that densified mixture design algorithm (DMDA) has been identified as a promising tool for green concrete mix design, its use in real practice has still been minimal worldwide. Due to the lack of precise information on DMDA computation in earlier studies, this work proposes DMDA including fly ash and ground granulated blast-furnace slag as a viable way to improve the long-term performance of green concrete. To encourage the use of DMDA, this study offers a detailed description of the DMDA mix design, as well as a step-by-step standard operating procedure and an empirical example of the computation. Assessments of the long-term performance of green mixtures (self-consolidating concrete and high-performance concrete) and ordinary Portland cement concrete (designed using the conventional method of American Concrete Institute, ACI) were made. Performances of the ACI (O6000 mixture) and DMDA concretes (S6000 and H6000 mixtures) were then compared in terms of compressive strength, elastic modulus, shrinkage, and creep strain. As a result, all of the concrete samples attained the target strength of above 41 MPa (6000 psi) after only 28 days. Moreover, compressive strength, elastic modulus, shrinkage, and creep strain increased significantly in all of the concretes over curing time. Importantly, the experimental results confirmed that both types of DMDA concrete exhibited higher compressive strength and better long-term performance than the ACI concrete under elastic modulus, creep, and shrinkage aspects.