Jarniewicz picked up the award at a ceremony in Warsaw on Sunday for his volume of poetry Mondo Cane.
Meanwhile, Joanna Ostrowska's Oni. Homoseksualiści w czasach II wojny światowej, a study of homosexuality during World War II, claimed the readers' choice award at the ceremony at the Warsaw University Library on Sunday night.
Seven books were in the running for the top prize this year, including three novels and a biography.
The Nike prize has been given out since 1997 to authors working in various genres.
Writers who have won the award in the past include Czesław Miłosz, Dorota Masłowska and Nobel Prize winner Olga Tokarczuk.
Last year the award went to writer and journalist Zbigniew Rokita for his book Kajś. Opowieść o Górnym Śląsku about Poland's southern Upper Silesia region, a melting pot of cultures.
(gs)
Source: PAP