These are the proceedings of the 5th International Scientific Conference on Information, Control, and Communication Technologies (ICCT-2021) which had been held October 4-7, 2021 in Astrakhan, Russian Federation. The main technical areas and applications covered by the proceedings are optoelectronics, acousto-optic, microwave technology, antenna systems, measuring technology, metamaterials, nanostructures, nanofilms, photonic crystals, biology and medicine, biophotonics, bioengineering, neural networks in communication technologies; 5G/6G systems; optical and millimeter-wave communication systems; defectoscopy and non-destructive testing of materials and devices for radio- and microelectronics; problems of reliability; automated control systems; diagnostics, etc. The Proceedings can be interesting for specialists in the communications and control systems.The conference had been held in a mixed format (online and offline) due to COVID-19. The organizing committee has chaired the meeting from Astrakhan (Astrakhan State Technical University). The conference included plenary talks (35 min for presentation and 5 min for questions for each speaker) and session talks (10 min for presentation, 5 min for questions). Fifty one speaker participated in the conference in person and ninety five speakers participated online via Zoom.List of Organising Committee, Program Committee are available in this pdf.