He was born on 10 November 1840 in Malá Divina (now Divinka) as the second of the eight children of his father Ľudovít and mother Jozefa née Nozdrovická.
His early ministry was spent in parishes in Lietava, Vysoká nad Kysucou, Bošáca and Zliechov.
Although his poetry was later published in two volume work Poesie Dušana Savy Pepkina, he was more recognized as the author of prose.
Medňanský was a member of numerous Slovak-affiliated philanthropic and patriotic societies (Radhošť, Muzálna slovenská spoločnosť, Dedičstvo sv.
[5] He was a co-organiser of collection for Museum in Martin, donated his library to Ľudovít Vladimír Rizner (one of founders of Slovak bibliography) and performed several similar cultural and national aware activities.