He indicated the costume was an attempt at raising awareness of what he felt was government control over Covid mandates.
The picture was posted by Darin Brown's wife, Jen Brown — who is running for council under the Tairāwhiti General Ward — with the caption "this is how you go to the supermarket".
Darin Brown told Local Democracy Reporting the photo was taken around the time of the first lockdown, and that he did in fact go to the supermarket wearing the outfit.
"I own it, man . . . I'm not a Nazi or white supremacist. I'm not an anti-vaxxer. Just the way they [the Government] went about pushing those vaccines on people, the first time in New Zealand history," he said.
"I've been getting a lot of slags because I support my wife. She advocates for those who have lost their jobs."
Other posts from Mr Brown included him saying he wanted to cut down 5G towers in January 2020, and writing expletives in October 2018 about people at the speedway letting off fireworks that scared his horses.
Mr Brown's posts were part of a Dropbox set up by former councillor Manu Caddie who encouraged members of the public to share questionable content they'd dug up.
Common themes include opposition to the Covid vaccine and anti-government rhetoric.
Mr Brown's wife, Jen Brown, also features heavily in the posts that have been compiled.
She told Local Democracy Reporting she didn't like the term anti-vax but was pro-choice.
However, in one post, Mrs Brown compared her "lucky rock" to the Covid vaccine in terms of its effectiveness in fighting the virus and criticised deputy mayor Josh Wharehinga for his stance on opposing the Wellington protest, which she attended.
She also called for a stop to the rollout of vaccines for children, and posted about a trans swimmer, critical of her competing against "biological women".
Mrs Brown said she was basing her campaign on bringing control back to local government — similar to her husband.
"I'm definitely not a right-winger or a racist. My husband is Māori," she said.
"I just took the test for where I sit [politically] and I'm a leftist liberal."
She confirmed she was a member of Voices for Freedom, a group that has encouraged its followers to run for councils to push its agenda.
Ben Florance — another candidate standing in the general ward — also attended the Wellington protest.
He said he wasn't originally planning on making the trip to the capital, but felt compelled.
"It was after I saw all the violence happening and I was like 'oh god, I have to get down there and try to do what I can to help, maybe make a bit of peace'."
At a candidate introductory event in Te Araroa on Wednesday, Florance introduced himself as a small business owner with a background in the military and Salvation Army.
On social media, he has shared content accusing the Prime Minister of having total control of the media.
He also shared a post titled "is Captain Cook our hero?" which claimed there would not be a New Zealand without him.
Florance would not address the question of whether Cook was his hero, but asked Local Democracy Reporting if they had read a history book.
Cook is a polarising figure. Nine Māori were shot and either killed or injured during his October 1769 visit to Tūranganui-a-Kiwa.
Leighton Packer, also standing under the general ward, attended the Wellington protest which she described as "peaceful".
In social media posts, she has accused the media of being "fake" and shared a post that labelled gay rights protesters "clowns".
Packer said the group was counter-protesting hers and felt some of their actions on the day were inappropriate for children to witness.
Peter Jones, a general ward candidate, shared on social media that there wasn't "a single party at the government who speaks for people who think Covid is a scam".
He did not wish to comment further.
The local government elections are set for October 8.
