A cross-border region is a key focus of many researchers representing various academic disciplines. However, the concepts of a cross-border region illustrated in the academic literature are not such as to demonstrate clear delimitation criteria. As a consequence, it is significant to carry out an in-depth analysis of the literature on cross-border cooperation, border theory, border regions and areas as well as borderlands in order to capture the essence and definition of the cross-border region. The aim of this study is to demonstrate the cross-border region as the highest form of border regions’ integration and to indicate its characteristics and delimitation criteria taking into account national borders’ functions, typology of border regions and cross-border cooperation.