This paper assessed the impact of illicit financial flow on economic growth and development in Nigeria. Data was sourced from the statistical bulletin of the Central bank of Nigeria and Global Financial Integrity estimates of illicit financial flows. Time series data from 1980-2015 was used. The variables were tested for unit root and co-integration and were found to have a long run relationship. The results further indicated that illicit financial flows had a significant impact both on economic growth and development. The study among others recommends that government of Nigeria and indeed other African countries must lobby developed nations to adopt control so that individuals who move funds out of Nigeria into tax havens and secrecy jurisdictions can be exposed. It was also recommended that African states and indeed Nigeria, in particular, must develop customs capacity in order to fight the massive outflows of capital through illicit practices.