Kyiv election commission declared Klitschko the winner on Monday, based on a complete vote count from the knockout round of the local elections the day before.
The former world boxing champion secured 66,5 votes, while his opponent Borislav Bresa, formerly a member of the extremist Right Sector, took 33,5 percent.
Klitschko also won the most votes in the first round of the ballot, on the 25 of October, but failed to win an outright majority against 28 other challengers.
The retired athlete is a political ally of the current Ukrainian president Petro Poroshenko.
Klitchko was first elected mayor of the Ukrainian capital in May 2014, after the former mayor resigned in the wake of the so-called Maidan revolution.
Previously, the 44-year politician was involved in the protest movement that sparked the crisis leading to the ousting of Ukrainian President Viktor Yanukovych.
Klitschko merged his UDAR party with Poroshenko's Solidarity in late August, in ahead of the local votes in October and November. He is also the head of the merged party.
dj/jil (Ukrainski Novini, AFP, Interfax, dpa)