Vasylenko was a sympathizer of the 1905 Revolution in Russian Empire and during the period he edited a newspaper "Kievskie otkliki" (Kyiv feedbacks).

For illegal fundraising to help workers of Saint Petersburg and Kyiv, support of 1905 sappers revolt in Kyiv, connections with revolutionary leaders, publication of articles of "anti-state" content in "Kievskie otkliki", Mykola Vasylenko was convicted to a year in prison which he served in Kresty Prison (Saint Petersburg).

At the time Vasylenko was a member of secret public organization and political alliance, the Society of Ukrainian Progressors.

However, due to "political unreliability" the imperial administration prohibited him to teach in higher educational institutions.

Around that time in 1910 Vasylenko joined the Constitutional Democratic Party that agreed to Ukrainian language in schools, courts, churches and promoted only the cultural autonomy of Ukraine.