President Emmerson Mnangagwa has won Zimbabwe's presidential election with 50.8 per cent of the vote, according to the country's Electoral Commission.

Six people died in an army crackdown on opposition protests after violence broke out when the Electoral Commission earlier announced the ruling ZANU-PF party had won a parliamentary majority in the election.

Mr Mnangagwa said he was "humbled" by his win in Monday's poll, the first after the fall of his former mentor Robert Mugabe.