Exemplary embodiments provide a prefabricated modular shower enclosure, including a base with a plurality of engagement feature along a peripheral surface of the base, a plurality of alignment supports, and a surround panel. In some embodiments, at least one alignment support is positionable in a preselected relationship relative to the engagement features of the base, and the alignment supports are configured to be independently made square relative to the base. Additional exemplary embodiments provide a prefabricated shower enclosure, including a base with a plurality of engagement feature along a peripheral surface of the base, and a plurality of surround panels that engage the base. The modular shower enclosure reduces installation time and complexity by using components that are fabricated and cut to size offsite prior to installation at a job site.