Agarista (Ericaceae) is currently represented in Peru by three species. Here, we update this number to five, based on the description of one new species and the report of one new record of a species and variety. The new species Agarista eugeniifolia differs from all congeneric species by an abaxially sulcate midvein. It is only known from one location in the province of San Marcos in Cajamarca Department. We also report A. mexicana var. mexicana as a newly recorded species and variety for both South America and Peru, with remarkable similarity to the disjunct nominate variety from Mesoamerica and noteworthy differences regarding leaf shape and short inflorescences in comparison to the other Peruvian Agarista species. Along with morphological diagnosis, description, and risk assessment of the new species, we provide a key to identify the Agarista from Peru, a map with the geographic distribution of the five species occurring in the country, illustrations, and taxonomic notes.