Revolution for Prosperity, a party set up only six months ago by businessman Sam Matekane, 64, won 56 out of 120 seats in parliament, according to final results published by the southern African country’s electoral commission.
The small mountain kingdom has been governed for the past decade by a string of coalition governments that have proved fractious and frail, and no premier has served out a full five-year term.
Matekane, who styles himself as a champion of the country's business community and was considered an outsider in the vote, came close to an outright win but will now have to secure the support of smaller parties to form a government.
The Democratic Congress party led by Mathibeli Mokhothu came in second, securing 29 lawmakers, according to the Independent Electoral Commission.
According to Lesotho’s electoral law, the party with more than 50% plus one of the votes would elect a prime minister and form the next government.
A new head of government will be appointed after the elections, but this will not necessarily end the long-standing political instability in this constitutional monarchy marked by a succession of coups and forced exiles, and where King Letsie III has no power.
Based on the early returns from polling stations, the RFP looks set to cruise to a landslide victory.
Final results are expected on Tuesday.