In March, Deputy Prosecutor General Jorma Kalske charged the city councilman over allegedly racist, anti-immigrant and anti-Muslim comments made on his blog in June 2008. Halla-aho, who was elected to the Helsinki City Council as an independent candidate on the ticket of the right-wing populist True Finns party, denies breaking any laws.
On Tuesday morning, Halla-aho appeared without a lawyer at Helsinki District Court, where he pled innocent to the charges.
Kalske is seeking a suspended prison sentence or fines.
Halla-aho had planned to run for European Parliament, but party chair Timo Soini successfully ran in his place after the charges were laid.
Halla-aho holds a doctoral degree in linguistics from the University of Helsinki.