On 20 July 1898, in New York City, he earned the title "Champion of America".
In the next year in Vienna, he became the European Champion in Greco-Roman wrestling.
In 1900, during the Exposition Universelle in Paris, he defeated the Frenchman Paul Pons and became a world champion.
He died in 1925 and was buried in his home town of Gorna Oryahovitsa.
Since 1963, a yearly tournament in the name of Nikola Petrov has been organized in Bulgaria.