This article provides a comprehensive review of various theories and hypotheses related to achieving an optimal capital structure. Researchers generally define capital structure as a combination of share issuance, private investment, bank debt, business debt, leasing contracts, tax obligations, retirement debt, deferred compensation for executives and employees, deposits, product-related debt, and other potential liabilities. The study explores key theories and hypotheses, including the Net Income Approach, Net Operating Income Approach, Traditional Approach Theory, Miller and Modigliani Theory, Static Trade-Off Theory, Asymmetric Information Hypothesis, Pecking Order Theory, Signaling Theory, Agency Cost Theory, Free Cash Flow Hypothesis, Dynamic Trade-Off Theory, and Market Timing Theory. Applying these theories enables analysts to maximize returns while minimizing risk, ultimately enhancing corporate value. Given the close relationship between profitability and capital structure, this paper emphasizes the importance of incorporating profitability factors in determining an optimal capital structure applicable across different financial environments.