The Central Electoral Commission (CEC) said on Monday that Petro Poroshenko had won the Ukrainian presidential election in the first round and officially declared him president-elect.

According to the finalized data, Poroshenko won 54.7 percent of the vote in the May 25 poll, against his closest challenger Yulia Tymoshenko's 12.81 percent.

The two frontrunners were followed by Radical Party leader Oleh Lyashko, head of the Civil Position Party Anatoly Grytsenko and former deputy prime minister Sergey Tigipko, who received 8.32 percent, 5.48 percent and 5.23 percent respectively.

Poroshenko is expected to be sworn in as the Ukrainian president on June 7 during an inauguration ceremony at the Independence Square in central Kiev.

The 48-year-old wealthy businessman and independent politician was the pre-poll favorite. Known as the "chocolate king," he controls the Roshen confectionery group. In 2013, his fortune was estimated by Forbes at 1.3 billion U.S. dollars.

Around 60 percent of the total 35.5 million eligible Ukrainian voters cast ballots in last Sunday's election.

The early election was called three months after former Ukrainian President Viktor Yanukovych was ousted in February and fled to Russia.