Sacroiliac (SI) joint implants for promoting SI joint fusion and methods of their delivery are described herein. The SI joint implant has a spacer operatively coupled to a planar member having tapered holes to receive fastening elements. When placed in the SI joint, the spacer engages the articular surfaces of the SI joint while the plate traverses the SI joint. The implant is held in place fastening elements, which are inserted through the tapered holes in the planar member. The implant is delivered via an inferior inlet MIS procedure, wherein the SI joint is accessed through an inlet inferior to the SI joint.