According to records available in the literature, 380 species of fungi and fungus-like organisms are known for the state of Quintana Roo on the Yucatán Peninsula of Mexico. We carried out mycological surveys in this state, following the classical methods for collecting, describing, and curating macrofungi. As a result of our research, 21 species are recorded for the first time for Quintana Roo, and Amanita arenicola O. K. Milller & Lodge, Inocybe xerophytica Pegler, and Russula cremeolilacina Pegler are recorded for the first time for Mexico. The distinctive characteristics and photographs are provided for the new records. As a result of this study, 401 species of macrofungi are known for Quintana Roo.