The challenge of lack of access to electricity especially in the rural areas of Nigeria is further compounded by the lack of cogent electrification plans. A fairly reasonable electrification plan should be able to model least-cost electrification technologies to be employed and give an estimate of investments required over a given period of time. The 2012 United Nation’s declaration of ‘International Year of Sustainable Energy for All’ highlights the importance of such studies and innovations, towards attracting funds from various sources for sustainable electrification projects. With the aid of a spatial electricity planning model called the ‘Network Planner (NP)’, this study identifies the appropriate least-cost electrification supply mode (grid, mini-grid and/or off-grid) and provides cost estimates for achieving universal energy access in Nigeria by 2030. Results from this research show that by the end of the 17-year planning period (2013 to 2030), 98% of currently unelectrified communities will be viable for grid expansion, while only 2% will be mini-grid compatible. An estimated total cost of US$34.5 billion investment is required to provide electricity access to a total number of 28.5 million households (125 million people) by 2030. The analysis was carried out for the 36 states of Nigeria as well as the entire country, using data from the 774 local government areas (LGAs) of Nigeria. This paper provides the foundation for the Nigerian Rural Electrification Agency (NREA) to develop an electrification plan as well as involve all stakeholders in carrying out direct surveys towards generating a database for rural electrification status in Nigeria.