In a telegram to Poroshenko, Merkel said the presidential elections in Ukraine were an impressive sign of the Ukrainians' will to promote freedom and self-determination in their country with democratic tools, Xinhua reported.
Merkel encouraged the new president in his goal of strengthening cohesion of the Ukrainian people, saying the German government would continue its support for his country in the future.
Poroshenko, a wealthy businessman and independent politician, is a former minister of trade and head of the council that runs the national bank.
Ukraine's Central Electoral Commission announced on Thursday that the 48-year-old businessman had won Sunday's presidential elections in the first round with 54.7 percent of the vote. He is expected to be sworn in June 8-10.