O.A. Borisenko is a leading geometer, one of the founders of the modern theory of submanifolds. His fundamental works, devoted to extrinsic geometry, the geometry of the Grassmannian image of submanifolds in Euclidean space, the geometry "in the large," the theory of mean curvature flows, and the theory of Alexandrov spaces, have gained wide recognition worldwide. He introduced new fundamental geometric concepts and constructions. Important achievements of O.A. Borisenko include solving a number of fundamental problems in the geometry of submanifolds, among which are the multidimensional Hilbert problem for isometric immersion of a compact Riemannian space of constant curvature into a Riemannian space of greater curvature, the Bernstein problem for two-dimensional minimal surfaces in a spherical space of arbitrary dimension, as well as proving the multidimensional generalization of Pogorelov's theorems on the uniqueness of general convex hypersurfaces in Riemannian spaces of constant curvature. O.A. Borisenko's scientific and pedagogical activity was for a long time associated with V.N. Karazin Kharkiv National University, where he progressed from student to professor and headed the Department of Geometry for 32 years. In the last decade, he has been working as the chief research fellow at the B.I. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine. O.A. Borisenko is the author of over 120 scientific articles, 5 reviews, 2 monographs, and 2 university textbooks. Under his supervision, 14 candidate dissertations have been prepared. O.A. Borisenko is a laureate of the State Prize of Ukraine in Science and Technology, the M.M. Krylov and O.V. Pogorelov prizes of the National Academy of Sciences of Ukraine, and has been awarded the Order "For Merit" III degree, as well as distinctions from the National Academy of Sciences of Ukraine "For Scientific Achievements," "For Professional Accomplishments," and "For Training Scientific Personnel," among other high honors.