Far-right activist and former neo-Nazi leader Kyle Chapman was arrested on Friday and charged with unlawful possession of a firearm and ammunition.
The former leader of the National Front claimed on social media he was raided and arrested, and it was "a miracle from God" that he was not held in custody.
Chapman said he was "looking at jail in future".
He also used the post to thank anti-vax lawyer Sue Grey for having his back.
Police confirmed a 52-year-old was arrested after a search was carried out at a Christchurch address on 8 September.
"He has been charged with the unlawful possession of a firearm and ammunition," a spokesperson said.
"He is due to reappear in Christchurch District Court on Thursday 28 September. As this matter is before the court, police are unable to comment further."