The incumbent gained 50.23 per cent of votes, Mongolia's General Elections Commission chief Sodnomtseren Choinzon said, after announcing that all ballots had been counted.
The result comes after election officials in Ulan Bator received information from all of Mongolia's 1,896 polling stations and from counters for overseas voters, but they would not be classed as official until the ballot papers were counted again on delivery to the capital, Choinzon said.
The Democratic Party candidate is expected to continue his policy of using foreign cash to power Mongolia's economy, which has been expanding rapidly in recent years.
The exploitation of Mongolia's vast coal, copper and gold reserves has helped transform an economy once characterised by nomadic lifestyles not far removed from its famous empire-building hero, Genghis Khan, 800 years ago.
But rising inequality in the cities and environmental damage in rural areas have dominated the political debate, while recent falls in commodity prices and slowing demand in the key market of China sparked uncertainty ahead of the election.
The third candidate, Natsag Udval from the Mongolian People's Revolutionary Party (MPRP),is the first woman to contest the presidency. She won 6.5 per cent, according to the preliminary figures.
