It's the first time an African government has canceled a major China-funded project
The project, which was due to be completed in 2022, had been commissioned by the previous president, Ernest Bai Koroma, just a week before an election in March that swept his party from power.
"After serious consideration and diligence, it is the Government's view that (it) is uneconomical to proceed with the construction of the new airport when the existing one is grossly under utilized," said a letter from the country's Minister of Transport and Aviation to the project's director.
Aviation Minister, Kabineh Kallon, told the BBC that the facility wasn't necessary and the current airport would be renovated instead.
He added that he did not know whether the cancelled contract would lead to financial implications.
China's ambassador to Sierra Leone, Wu Peng, said that relations would not sour between the two countries.
"I don't think the airport project should affect our future bilateral relations," he was quoted by the BBC as saying.
Sierra Leone's decision is the first time an African government has canceled an already announced, major China-backed deal.
China has been considered a good partner by many African countries even though there is worry that its loans are burying some of these countries under massive debt.
The East Asian nation has, however, denied engaging in "debt trap" diplomacy adding that it continues lending to Africa on the grounds that the continent still needs debt-funded infrastructure development.