Dolniak is a surname. Its origin is Slavic, meaning "valley dweller." Its counterpart, Hornyak, means "mountain dweller." Notable people with the surname include:
- Barbara Dolniak (born 1960), Polish politician, wife of Grzegorz
- Grzegorz Dolniak (1960–2010), Polish politician
- Nick Dolniak (born 2000), South Bend, IN celebrity