As a kind of material used in river revetments, the revetment concrete blocks are required to have satisfactory strength, scouring resistance, and good vegetation coverage. In this paper, prefabricated grass-planting concrete blocks that are suitable for the ecological revetment of medium and small-sized rivers are proposed and innovatively designed. The blocks are made with concave and convex structures of random porous concrete material, which can be jointed and inlaid to form a three-dimensional slope with vegetation function. The performances and advantages of prefabricated grass-planting concrete are evaluated. Four kinds of precast blocks are proposed. The flow velocity reduction, soil conservation, and scouring resistance of these blocks are analyzed quantitatively through physical modeling and field application. The results show that the four blocks can effectively reduce the near-shore flow velocity and decrease the level of scouring on the slope surface. The rate of scouring reduction of the different prefabricated blocks placed on the slope was in the range of 35%-43%; thus, the results were similar. Through application on a riverbank, this concave-convex revetment structure shows excellent improvement in scouring resistance and soil conservation, with average vegetation coverage up to 95%. Prefabricated grass-planting concrete blocks can be used as riverbank revetment materials.