Monetary policy in Nigeria affects the stock market development. The study used tests to show that the Monetary Policy Rate, Broad Money Supply, and Per Capita Income have a significant long-term relationship with the Nigerian Stock Market. The researchers suggest that the Central Bank of Nigeria should have a consistent long-term monetary plan to avoid market instability caused by frequent money mop-ups. Reducing the gap between targeted and actual broad money growth can help stabilize the stock market for investors.