E-commerce has seen significant growth since the outbreak of the COVID-19 pandemic. This has led to changes in consumer preferences and increased pressure on companies to develop effective e-commerce and social media capabilities to retain customers. This study examines the impact of these capabilities on customer retention and firm performance by collecting quantitative data from 160 small U.S. e-commerce companies in the fashion industry. The study finds that customer retention positively relates to firm performance and that factors, including cross-device shopping, payment methods, page speed, standard delivery time, Pinterest activity, and Instagram activity, significantly impact customer retention. The study suggests strategies for companies to remain competitive in the dynamic e-commerce landscape.