The landmark case involved comments made about Erwin Kessler, the head of an animal protection group.
He was accused of being anti-Semitic and racist, media reports say.
The Zurich district court said the defendant "clearly endorsed the unseemly content and made it his own" by liking comments.
The 45-year-old man liked six comments, according to Swiss newspaper Le Temps.
Mr Kessler is reported to have sued more than a dozen people over various comments made on Facebook in 2015.
