According to the invention, there is provided a novel soybean variety designated RJS21002. This invention thus relates to the seeds of soybean variety RJS21002, to the plants of soybean RJS21002 to plant parts of soybean variety RJS21002 and to methods for producing a soybean plant produced by crossing plants of the soybean variety RJS21002 with another soybean plant, using RJS21002 as either the male or the female parent.