This study examines the factors influencing retail investors’ decision to invest into the Indian pharmaceutical sector amidst the COVID-19 global health crisis. Confronting the obstacles introduced by the pandemic has helped create a robust foundation for the Indian pharma sector to grow rapidly in the future. As the industry demonstrated signs of considerable future growth, investors favored pharmaceutical investments during COVID-19. Retail investors were mainly the ones who went on a shopping spree during the pandemic. This backdrop provides a unique context to explore the retail investors’ behavior in the Indian pharmaceutical landscape. Leveraging the Theory of Planned Behavior (TPB), this study marks the first attempt to introduce behavior toward market fundamentals as a mediating factor into the TPB framework. To conduct the study, data were collected from 305 retail investors located in Karnataka’s South Canara region, who invested into the Indian pharmaceutical industry during the pandemic, using snowball sampling. The e-survey was employed for data collection. The results reveal that attitudes toward pharmaceutical investments, subjective norms, Perceived Behavioral Control (PBC), and behavior toward market fundamentals have significantly influenced investor decisions. Notably, behavior toward market fundamentals has partially mediated the relationship between attitude toward pharma investment and investment decision and PBC and investment decision. However, the mediation effect of behavior toward market fundamentals was not evident between the subject norm and the investment decision. The study holds pivotal implications for policymakers, government bodies, and industry stakeholders to promote pharmaceutical investments.