According to the invention, there is provided a novel soybean variety designated XB31J07. This invention thus relates to the seeds of soybean variety XB31J07, to the plants of soybean XB31J07 to plant parts of soybean variety XB31J07 and to methods for producing a soybean plant produced by crossing plants of the soybean variety XB31J07 with another soybean plant, using XB31J07 as either the male or the female parent.