The aim of the paper is to analyse the main internal drivers of the increase and adoption of online activities carried out by firms in reaction to the Covid-19 pandemic. While the impact of Covid-19 pandemic on several measures of firm-level performance has been debated in many papers, not enough effort has been devoted to investigating its digitalization impact, especially with respect to the drivers of firms operating in transition countries. To this end, we explore a very detailed firm-level dataset, drawn from the World Bank Enterprise Survey (WBES) combined with the Covid-19-ES Follow-up Survey, for 22 Eastern European and Central-Eastern Asian countries. Our findings reveal that (i) higher online activity is associated with higher digital and technological endowment of the firm and (ii) this relationship is shaped by external factors, such as country-level digital infrastructure.