This study analyzes competition among three major e-commerce platforms in Indonesia - Shopee, Lazada, and Tokopedia - using the Markov Chain model. The primary focus is to evaluate the marketing mix, including price, promotion, security, service, and product availability, within the Mataram City e-commerce market. Data on consumer use of these platforms are analyzed to predict market share and consumer behavior over time. The findings demonstrate how the Markov Chain model can predict shifts in market share among these platforms and provide insights into the future effectiveness of their marketing strategies. This model enables companies to optimize promotional costs and refine marketing approaches, preparing them to compete in an increasingly competitive market.