Electoral democracy rests on several critical universal principles, including popular participation, a free, fair, transparent, and accountable electoral process, which defines the extent to which an election is deemed credible. It is therefore the quest to achieve credible elections, particularly in developing democracies, that spurs the need for local and international election observation and/or monitoring, an activity which found its way into Nigeria’s electoral process in 1999 when the country returned to party politics after 16 years of uninterrupted military rule. It is in the light of this background that this chapter examines the participation of international election observers in Nigeria’s electoral process and their promotional activities in deepening election administration in Nigeria’s current democratic dispensation. The study argues that despite criticisms surrounding the activities of international election observers in Nigeria, it is evident that their interventions have shaped successive elections since 1999 through reforms that have led to innovations that continue to strengthen the nation’s electoral process. The study adopts democratic promotion theory as its theoretical analytical framework, while the research methodology is qualitative, with data sourced from books, journal articles, official institutional reports, and the Internet. Data collected are descriptively and thematically content-analysed.