Brenton Tarrant, who appeared by video link, entered his plea through his lawyers.
The High Court Justice Cameron Mander said the trial will commence on May 4 next year. Tarrant has been remanded in custody until Aug. 16 when a case review hearing is scheduled.
In an attack broadcast live on Facebook, a lone gunman armed with semi-automatic weapons targeted Muslims attending Friday prayers in Christchurch on March 15, in New Zealand's worst peace time mass shooting.