Financial decision of a firm has continued to constitute concern amongst managers, analysis, researchers, scholars as well as policymakers. This study investigates the Effect of Firm Specific Characteristics on Financial Leverage of Quoted Diversified Companies in Nigeria. The population of the study is the six (6) Diversified Firms listed on the Nigerian Stock Exchange as at 31st December 2014. The study took a census approach of all the six (6) Listed Diversified Firms over the period of the study. Multiple regression technique using Ordinary Least Square (OLS) was employed in analyzing the panel data obtained from audited annual reports and accounts of the sampled firms for the period 2007-2014. The findings of the study revealed that, complexity of business, profitability, growth opportunity and the moderating effect of growth opportunity and profitability on financial leverage were found to be statistically significant. Dependency on external finance, the moderating effect of growth opportunity and complexity of business on financial leverage and the moderating effect of growth opportunity and dependency on external finance on financial leverage were found to be statistically insignificant. The study recommends among others that, management of quoted diversified companies in Nigeria should encourage diversification in line of businesses that their streams of revenue or income are not positively correlated. This can be done by seeking growth opportunities in industries where they can further diversify their business to break in revenue or which will allow them to conveniently finance their subsidiaries and reduce their bankruptcy risk through borrowing