At the beginning of the twentieth century in the Russian-speaking philosophical space philosophical projects emerged which brought ontology and gnoseology closer together. One can observe this process, for example, in the philosophical doctrines of the Russian intuitivists Nikolay Lossky and Semyon Frank. I demonstrate that the emergence of these doctrines and the development of their onto-gnoseological categorial apparatus were mainly connected with the criticism of the Neo-Kantian theory of cognition and the possibility of transcendent knowledge as such. The main sources of my study are The Intuitive Basis of Knowledge and The World as an Organic Whole by N. O. Lossky and The Object of Knowledge and The Unknowable by S. L. Frank. My investigation makes it possible to treat Lossky’s categorial framework as the representation of a system of levels of the universe each of which is characterised by two aspects: the ontological, i.e. it is part of the unity of the world, and the gnoseological, i.e. it has an independent cognitive significance. Frank considers categories to be an organic part of the ontological proof of intuitivism. A common trend in the construction of categorial schemes by Lossky and Frank is their striving to combine gnoseological and ontological descriptions of categories. The key difference is the way an onto-gnoseological system as a whole is justified. In revealing the contradictions in Lossky’s conception, I proceed from the critical remarks of S. A. Askoldov, pointing out that these contradictions stem from an absolutisation of intuition in cognition, the renunciation of the idea of gnoseological transcendence, incompleteness of the theory of immanence and discordance between onto-gnoseological categories. Askoldov’s critical comments clarify the substantive features of Lossky’s theory and the essence of the transformations carried out in Frank’s absolute ideal-realism.