This book constitutes the revised selected papers of the Third International Conference on Innovations in Digital Economy, SPBU IDE 2021, held in St. Petersburg, Russia, in October 2021. The 23 papers presented were thoroughly reviewed and selected for publication from 153 submissions. The papers are organized according the following topical sections: economic efficiency and social consequences of digital innovations implementation; regional innovation systems and clusters as drivers of the economic growth during the Fourth Industrial Revolution; industrial, service and agricultural digitalization; response of an educational system and labor market to the digital-driven changes in the economic system; digital transformation trends in the government and financial sector.