This study x-rayed agricultural sector as the engine of economic growth in Economic Community of West African Countries (ECOWAS); more so as the agricultural sector employs over 70% of the labour force and provides the means of livelihood for the greater population in the region. Furthermore, it is the believe that improvement in the agricultural sector productivity will likely enhance the per capita GDP growth of the ECOWAS. Data was collected using documentary evidence (secondary data). Time series methods of analysis such as panel unit root tests, panel co-integration test, panel co-integration regression method using fully modified ordinary last squares (FMOLS) model were employed for the analysis. The variables analysed include the GDP per capita (the dependent variable) and agricultural sector output per capita, capita stock per capita, industrial sector output per capita, services sector output per capita and government expenditure per capita (independent variables). The results established that agricultural sector output per capita, capita stock per capita and economic institutions exert no significant impact on per capita GDP of ECOWAS. However, government expenditure, industrial sector output and service sector output, all measured on per capita basis, significantly impacted on ECOWAS countries per capita GDP growth. The study concluded that only Government provision of services per capita, and industry sector output per capita significant stimulated growth in ECOWAS countries. Capital stock per capita and economic institutions did not. The study recommended efficient resources investment and functional institutions to further promote growth in the ECOWAS countries.