The railway will be built along the West African nation's coast, Chinese state news agency Xinhua said on Thursday.
The announcement comes shortly after Mexico abruptly scrapped a 3.75 billion dollars high-speed rail contract with a consortium led by the Chinese firm over transparency concerns.
China is pushing to win railway construction projects around the world as part of plans to export its high-speed technology and lift its manufacturing sector up the value chain.
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Beijing is also pumping money into the sector, with more than 100 billion dollars’ worth of infrastructure projects approved in late October and early November in a bid to bolster slowing growth in the world's second largest economy.
"It is a mutually beneficial project," CRCC Chairman Meng Fengchao told Xinhua. He added the railway project will lead to equipment exports from China worth $4 billion, including construction machinery, trains and steel products.
Officials at CRCC could not be immediately reached for comment.
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The project will create up to 200,000 local jobs, according to Xinhua, helping Beijing in its soft power push to gain a foothold in resource-rich regions of Africa.
The coastal railway will stretch for 1,402 kilometres, linking Nigeria's economic capital Lagos in the west with Calabar in the east, Xinhua said.
CRCC's Shanghai-listed shares were up 1.5 per cent at 1300 in Shanghai (0500 GMT), outperforming the wider CSI 300 Index, which was down 0.1 per cent.