The mandate of the ECOWAS Electoral Assistance Support System (EEASS) to promote sustainable democracy in member countries is being undermined by intense internal political complications. Certainly, West African countries are maturing into stable political transitions but there is still the problem of distortion of democratic principles to subvert the collective will of the people. The aim of this study was to assess the effects of the EEASS on sustainable democracy in member countries. The objectives of the study were to: (i) examine the main thrusts of the EEASS to member countries; (ii) investigate the extent to which members have domesticated the Good Governance requirements for EEASS; (iii) evaluate the extent to which members have benefitted from the EEASS; (iv) assess the effects of EEASS on sustainable democracy in member states; and (v) identify the challenges of EEASS in member countries.rnThe study adopted mixed method research design, consisting of quantitative and qualitative data collection techniques. Questionnaire was used to collect quantitative data while Key Informant Interview (KII) and Focused Group Discussion (FGD) were employed to generate qualitative data. The total ECOWAS total population was around 500 million people while the sample size for the study consisted of 500 randomly selected respondents from relevant electoral stakeholders. The data analysis for the study was based on the 485 copies of retrieved questionnaire and responses from the KII and FGD. The data collected were interpreted with the use of percentages and descriptive analysis. The reliability of the results (0.88 reliability value) was obtained through the use of inter-instrument data consistency model. The data gathered were analyzed using the Statistical Package of Social Sciences (SPSS).rnThe findings of the study were that:rn(i) The EEASS to ECOWAS member countries included election observation (96%), improved performance capacity building for electoral umpire (87%) and financial assistance 48%;rn(ii) most member States (89%) have domesticated the values of ECOWAS good governance requirements for accessing its electoral assistance by adopting zero tolerance to non-democratic governance (93%), increasing freedom of political association (82%), improving free and fair elections (40%) and reducing electoral violence (34%);rn(iii) many member States (67%) have benefitted substantially from the EEASS with training support for their electoral commission (83%), financial assistance (67%), post election crisis management workshop (64%) and capacity building on credible election observation methods (52%);rn(iv) the EEASS has positive effects on sustainable democracy in member countries having led to overwhelming reduction in coup dâ€™Ã©tat (92%), increased stable democratic transition in member countries (81%) and reduced electoral violence (36%); andrn(v) the challenges of EEASS at enthroning sustainable democracy in member countries included poor funding of electoral administration (89%), weakrnelectoral policing (87%), partial electoral umpire (84%) and bad governance (82%).rnThe study concluded that the ECOWAS electoral assistance support system has served as a useful political tool for enthroning sustainable democracy without adequately enhancing accountable governance. The study recommended that the EEASS be sustained and refocused for better performance in West African States.