The effectiveness and efficiency of the board of directors as a monitoring tool to the management of an organization is essential to the performance of the firms. Given that board efficiency is subject to its structure, it therefore becomes imperative for studies to empirically ascertain the relationship between leadership structure, ownership concentration and firm size on financial performance of listed insurance firms in Nigeria. The population comprises all the quoted insurance firms in Nigeria while filtering technique was used to arrive at a sample size of twentythree (23) listed insurance firms in Nigeria. The hypotheses were tested using robust random effect regression model after conducting some diagnostics tests. The findings regarding Leadership Structure, Ownership Concentration, and Firm Size align with much of the existing literature that suggests these factors play significant roles in shaping firm performance, including ROE, in the context of insurance companies in Nigeria. These results underscore the importance of effective corporate governance practices, ownership structures, and strategic positioning in influencing financial outcomes. However, it's important to note that the impact of these factors can vary based on specific contextual factors, such as regulatory environment, market conditions, and industry dynamics. Future research could further explore how these relationships evolve over time and in response to external shocks or policy changes affecting the insurance industry in Nigeria. The study recommends among others, that Management of Insurance companies should Ensure that the board of directors is diverse and includes members with relevant expertise in insurance and finance. This diversity can bring different perspectives and enhance decision-making processes. Consider separating the roles of CEO and board chair to promote checks and balances within the leadership structure. This separation can enhance governance and accountability. Management of Insurance companies should Encourage a balanced ownership structure that avoids excessive concentration of control among a few shareholders. This can mitigate risks of entrenchment and promote transparency and alignment of interests. Foster active shareholder engagement and participation in corporate governance processes to ensure effective monitoring and oversight of management decisions