The privatisation of most of state electricity firm PHCN has long been in the works in Africa's most populous nation, where blackouts occur multiple times daily despite the country's status as the continent's largest oil producer.
Those taking over assets include Seoul-based Korea Electric Power Corporation as well as local investors.
Separately, the deal with the Chinese government involves construction of a hydroelectric plant expected to add 700 megawatts to the national grid.
It is not clear if the new plant will remain in state hands or if it too will be privatised.
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Nigeria has portrayed the privatisation of electricity generation and distribution as a reform capable of finally bringing steady power supplies to the country, where businesses are forced to rely on diesel generators to cope.
President Goodluck Jonathan today handed over operating licences to investors for most of the companies created from the splitting up of the former Power Holding Company of Nigeria (PHCN).
A power generation firm not part of PHCN was also handed over, while various issues are yet to be resolved for the two other generation firms and one distribution firm.
Nigeria will retain ownership of the national grid, but privatise its management. Canada's Manitoba Hydro International was named its manager for three years in 2012.
"Today, therefore, not only concludes legal transactions, it is a day of hope, a day of promise and a new beginning for one of the most vital sectors of our national economy," Jonathan said.
The privatisation of telecommunications in Nigeria is generally credited with bringing improved service and accessibility to the country.