Institutions, institutional infrastructure are becoming of special importance under conditions of digitalization and hybrid war, ensuring viability, security and competitiveness of almost every state’s economy in the 21st century. Unlike traditional («hard») infrastructure (roads, ports, bridges, airports, tunnels, power lines, pipelines etc.), institutional («soft») infrastructure is not that distinguishable, but its functioning is often more crucial in the context of globalization, internetization, cybernetization, economic security. Internet as the global metainstitute (net of the nets, world wide web) that encompasses specific formal and informal rules, institutions of development and/or institutions of growth, «key institutions», ecosystem, digital markets: AeroNet, FoodNet, AutoNet, MariNet, HealthNet, EnegyNet, SafeNet, FinNet, NeuroNet – all these and many other institutions have become inalienable attributes of the «digital» economy that strives to overdrive today. NeuroNet will substitute Internet in the long run, when human-machine interaction transforms into the human-machine interconnection. Theoretical and practical «digital» economy institutional fundamentals research results in the context of institutional infrastructure are represented in the article. Institutional fundamentals are perceived as a set of organisations (Yandex, Mail.ru, KASPERSKY etc.) that produce information and communications technologies – ICT as well as knowledge-intensive services (Sberbank-Technology, ROSNANO etc.), biotechnological sector, electronics, avionics, robotics. Original approved authorial interpretation of institutional infrastructure as emerging holistic system involving Internet, artificial intelligence, nine abovementioned digital markets, definite economic mechanisms (digital platforms, clusters etc.), technological cooperation, specific organizations (for instance, All-Russian supercomputer scientific and research data center on the basis of the Russian Academy of Sciences, scientific and technological centre («digital valley»)) is provided. Technological essence of the «digital» economy as internetized, cybernetized mechanism (based on digital technologies), producing digital goods and digital capital, is defined. Necessity of competitiveness improvement and some opportunities of national economic security assurance are substantiated from the standpoint of practical novelty.