Built by Africa's richest man Aliko Dangote in the commercial hub of Lagos, the refinery - with the ability to process 650,000 barrels a day when at full capacity - should begin operations in June.
The new facility, lying on 2,635 hectares of land at the Lekki Free Zone and costing an estimated $19bn according to local media, could be a game changer.
The refinery, which was first scheduled to open in 2021, will "stop the drainage of foreign exchange" and "create massive employment," a senior manager with Dangote who did not want to be named told AFP.
He said the project will "meet the entire requirements of Nigerians," and serve needs around the world.
"We have (the) capacity to export the products to any part of the world. We have two vessels to bring in the crude, three vessels to export it to any part of the world," he said.
Some 1,100-kilometers of subsea pipelines have been laid to link the oil-rich Niger Delta to the complex.
The pipelines are also expected to create a corridor for the evacuation of trapped gas from offshore platforms and allow for the monetization of the product.
Also on the massive complex is a $2 billion fertilizer plant with a three million tons per annum capacity.
For decades, Africa's most populous nation and one of the continent's largest crude producers has depended on imports to meet local demand because of under-performing state-run refineries.
Nigeria swaps crude worth billions of dollars for gasoline it then subsidizes for its domestic market.
It has caused a huge drain on foreign exchange at a time of dwindling oil revenue following the coronavirus pandemic and the Russia-Ukraine war.