The contract is China's single largest overseas project, China Railway Construction Corp Ltd (CRCC) said.
Earlier this month, CRCC lost a USD 3.7 billion contract to build a high-speed rail link in Mexico after the country's legislature raised concerns about the nature of the bidding process.
Chinese state-owned enterprises have invested hugely in Nigeria's infrastructure, including in its oil and telecommunications sector, and elsewhere in Africa over the last decade.
Trains will travel at a top speed of 120 km per hour, according to the CRCC.
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"It is a mutually beneficial project," CRCC chairman Meng Fengchao said, adding that the coastal railway project will adopt Chinese technological standards and result in equipment exports worth USD four billion , such as construction machinery, trains and steel products.
"Meanwhile, the project will create up to 200,000 local jobs, directly or indirectly. Up to 30,000 fixed job posts may also be provided when the railway is operational," Meng said.