The aim of the article. The purpose of this paper is to study the impact of extreme situations such as the COVID pandemic on the development of e-commerce business models and identify ways for their successful transformation in Ukraine so as to ensure sustainable development in crisis conditions. Analyses results. Business models (BM) are models of a business system activity, which is always aimed at meeting certain needs. The crisis driven by the pandemic the Covid-19 caused changes in consumer needs and requirements for the ways of their satisfaction, which could not but lead to innovative changes in e-commerce business models. Redesigning or creating a new BM means creating new model components (target customer segments, value propositions, delivery methods, revenue models, key activities, etc.) and/or rearranging the main BM components. To estimate the impact of the pandemic on different types of e-commerce business models, we assessed changes in their components based on the Osterwalder framework. The analysis of these changes showed that the most significant innovations occurred in such components as key consumer segments and needs, which the value proposition is to meet, and, as a result, the value proposition itself as well as the channels of value distribution and ways of interacting with customers. Changes in other components, in particular, revenue generation, appeared to be secondary, although necessary for technological support of renewed business models. Under restrictions on physical contact, new key consumer segments have emerged. Changes in consumer priorities and requirements have forced e-commerce businesses to reconsider their priorities and product mix, complementing their product offerings with related services, and to refocus their BM, partnerships and terms of cooperation. Analysis of the experience of successful e-tailers has shown that the pandemic has led to fundamental changes in the value proposition beyond the change in assortment and digitalisation of the value proposition, including: 1) replacing the offer of a value available for purchase with the value delivered/provided to the consumer; 2) expanding the value proposition to include its visualisation, its virtual testing or virtual use; 3) transition from offering real products to offering their virtual analogues; 4) expanding the value proposition of a product or service through socialisation and gamification of the process of choosing and purchasing goods in e-commerce to restore the social experience lost during the pandemic; 5) transforming the process of choosing and purchasing value into a value proposition itself; 6) creating a purely virtual value proposition for virtual buyers in the form of a package of virtual goods and services without physical analogues, with their further testing and purchase without or with replacement with material copies of virtual products. The need for cheaper, faster and more contactless processing and delivery of a large number of orders prompted the development of automated warehouses: the dark store business model gained in popularity; the format of fast delivery on demand was developed, including for goods that were never supplied in such a way before (food deliveries from restaurants). The dark store model and the innovativeness of its elements are studied. It is also shown that under conditions of decreasing buying ability, it proved advisable to introduce the “Buy now, pay later” (BNPL) service into the e-merchant model, creating a sustainable business ecosystem centred around the online merchant and the BNPL provider platform. It is shown that the most successful in adapting their business models to the challenges of the pandemic appeared to be multivendor marketplaces that implemented the BNPL service and rebuilt their logistics. Conclusions and directions for further research. Although almost all disruptive innovations in e-business models had been made in the pre-covid period, a lot of supporting innovations were stimulated by the challenges of the Covid situation. Changing target segments, needs, and consumer preferences have forced e-businesses to update value proposition, customer relationships, delivery channels and revenue models, with appropriate changes in business models based on the use of the most advanced digital technologies. At the same time, pandemics are not the only unpredictable global factor affecting the development of entrepreneurship in general and e-commerce business models in particular; the impact of other extreme situations, either natural, epidemiological or socio-political, is also significant. The effective adaptation of Ukraine's e-commerce business models to the impact of extreme situations such as military conflicts of various scales is gaining particular relevance, and the ways to achieve this should be the subject of further research.