The study examined the impact of insurance companies' investment on bank liquidity and economic growth of Nigeria. This is basically to determine the extent of insurance companies contribution to liquidity formation in the banking sector which has being the major cause of bank failures as a financial intermediary and a dealer in short-term securities thereby mobilizing resources for real economic sector. The population of the study is made up of the fifty-nine Nigeria (59) insurance companies in Nigeria. Time series data from the central bank statistical bulletin on total insurance business investment was the source for secondary data. The study employed both inferential and Descriptive Statistics. The E-view statistical package was used for data analysis and test for three (3) hypotheses. The study reveals that there is no significant relationship between short-term investments of insurance companies and banks liquidity, that there exist no significant relationship between short term investment of insurance companies and liquidity formation of the Nigerian money market. The study also reveals that there exist a positive but not significant relation between insurance premium and Gross Domestic product in Nigeria. The study concludes that insurance companies in Nigeria do not impact significantly on the liquidity of banks, money market and economic growth in Nigeria. The study recommends that insurance companies be recapitalized to afford them more resources to expand their investment portfolios to stimulate liquidity formation. That the insurance companies should be more innovative and provide more services to courte public attention and participation to close the insurance gap. The National Insurance Commission (NAICOM) should also ensure compliance and adherence to regulations in the industry.