 In 1898 Mikhnovsky moved to Kharkiv, where he became a lawyer and a prominent Ukrainian independence activist.In 1900 he became one of the founding members of Revolutionary Ukrainian Party, which became the first Ukrainian political party under Russian rule.In response to the spread of Marxist ideas in RUP, in 1902 some of its members organized a new organization called Ukrainian People's Party, of which Mikhnovsky became a leader.