Former university rector Giorgi Margvelashi's victory in the election consolidates the power of Prime Minister Bidzina Ivanishvili in the US-aligned former Soviet republic.
The results posted by Georgia's Central Election Commission, with more than 90% of precincts counted, are in line with exit polls.
The candidate from outgoing President Mikhail Saakashvili's party finished second with 22%, which is higher than expected.
Mr Saakashvili did not wait for the official results to congratulate his successor.
Mr Ivanishvili has kept Georgia on track towards greater European integration and maintained close ties with the US.
European observers gave the election a clean bill of health, saying it was "positive and transparent".