A universal inside corner patch for patching inside corners formed by protrusions from a commercial low slope roof is disclosed. The universal inside corner patch includes a body having a central portion and a peripheral portion. A cutout is formed in the body extending from the peripheral portion to the central portion thereof. The cutout defines in the body a skirt having an edge on one side of the cutout and a flap having an edge on an opposite side of the cutout. Folding locations such as lines or other indicia on the body correspond to respective angles of an inside corner to be patched. When the skirt portion is overlapped with the flap portion with the edge of the skirt portion registering with one of the folding locations, the inside corner patch is configured to conform to an inside corner with an angle corresponding to the one of the folding locations. An adhesive may be disposed on a back surface of the body for adhering and sealing the corner patch in place.