This study aims at exploring the benefits of using dolomite powder (DP) to improve the engineering performance of low-cement self-compacting concrete (SCC) with cementitious materials comprised of 50 wt% of ordinary Portland cement (OPC) and 50 wt% pozzolanic materials of ground granulated blast furnace slag (GGBFS/slag) and low calcium fly ash (FA). Experimental results showed that the DP addition to partially substitute for the pozzolanic materials had no impact on the setting properties of pastes with blended binder of slag and OPC while significantly improved those of the pastes with that of FA and OPC or ternary mixture of slag, FA, and OPC binder. In addition, the adjustment of DP addition to the above-mentioned three binders had successfully manufactured the self-compacting mortars (SCMs) with significant increase in the flowing ability and compressive strength, in which the DP addition of 30 wt% substituting for the total amount of pozzolanic materials resulted in the hardened mortars with highest compressive strengths after ages of 7 days. The improvement of compressive strengths of hardened SCMs can be obtained by the DP addition up to 50 wt%. The SCCs produced from the appropriate proportions of the resulting DP modified SCMs had the engineering properties mostly satisfying the technical requirements for practical concrete structures.