In a rapidly changing Indian stock market environment, investors are increasingly faced with complex choices regarding investment opportunities, risk assessment and return expectations. This study, titled “A Study On Impact Of Investment Decisions In Stock Market Of Investors” aims to analyze the factors influencing investors\' decision-making processes and evaluate how these decisions affect their investment performance. This study adopted a descriptive and analytical research design that integrated primary and secondary data sources. Primary data is collected through a structured questionnaire administered to 100 individual stock investors, and secondary data is collected from financial statements, stock market publications, and reliable online sources over a period of 10 years (2016-2026). Key variables such as risk tolerance, investment horizon, market knowledge, behavioral biases, and return expectations are considered to assess their impact on investment decisions. This study uses statistical tools such as correlation analysis, regression analysis, and percentage analysis to investigate the relationship between investor behavior and investment performance. Qualitative aspects such as investor awareness, emotional influence, and market sentiment that shape decisions are also considered. Preliminary results indicate that investment decisions are strongly influenced by factors such as risk perception, financial knowledge, and behavioral biases. While some investors achieve favorable returns through sound and strategic decisions, others experience inconsistent results due to emotional and impulsive behavior. This study provides valuable information to retail investors, financial advisors and policy makers, highlighting the importance of informed decision-making, risk management and investor education for successful sustainable investment in the stock market.