Orthopteroidea is an ecologically diverse group of incompletely transformed insects that includes several insect orders similar in development and structure. Many species from Dermaptera, Orthoptera, Mantodea, and Blattodea are sensitive to anthropogenic influences and are indicators of the external environment. Some species cause damage to agriculture and forestry; others are inhabitants of human dwellings and pests of food supplies. The aim of this study is to describe fauna of some orders of Orthopteroidea in the Republic of Mordovia, in the central part of European Russia. This study was conducted in April–October 1971, 1984, 1995, 1996, 1998, 2000, 2001, and 2004–2023. All possible habitats were studied using a variety of methods (entomological traps, pitfall traps, pan traps, etc.). An acoustic method of species identification was also used. For each observation, the coordinates of location, abundance, and dates were recorded. The dataset contains 4865 occurrences. In total, 16,644 specimens of Orthopteroidea were studied. The dataset contains 71 species including Dermaptera (4), Orthoptera (62), Mantodea (1), and Blattodea (4). Of these, 13 species are identified for the first time in the region; these mainly inhabit steppe areas. The presence of two Orthoptera species has not been confirmed yet during our studies; these species are noted in this paper according an old published paper. The biodiversity of Mordovia includes 73 species from four orders. The biology of numerous species, their seasonal dynamics, and some descriptions of biotopes and number of new species are described.