Three slogans on Wicked Campers have been ruled R16 by the Chief Censor and are now "objectionable publications".
Associate Minister of Tourism Paula Bennett, who has led the campaign against the vans, has declared the move a "victory".
"It's something I believed in and there wasn't an easy solution to it. It does feel good being part of finding one. This is a real victory for everyone that has seen the vans and been offended by the awful slogans and images on them.
"This will send a clear message to Wicked Campers that their offensive slogans are not welcome here and it's time they cleaned up their act."
The ruling against the three slogans means Wicked Campers faces a fine of up to $200,000 for each instance in which its vans are caught out in public.
Enforcement is down to the police, which was the agency that raised the issue with the Chief Censor.
Ms Bennett said slogans which promoted drug use and sexual violence "totally overstep the mark".
She said further rulings were to come from the Chief Censor with the current three being those issues first raised.
The vans affected by the ban are those carrying slogans which linked drug use to children. One carried an image of Snow White using what appeared to be a crack cocaine pipe while another featured cartoon characters Scooby Doo and Shaggy smoking marijuana.
The third van to have its slogan banned showed a Dr Seuss character also talking about smoking marijuana - words on the van attributed to the character were "I did a bong, I did, I did".
Other slogans which have raised community ire include the following: "In every princess there is a little slut who wants to try it just once"; "Fat chicks are harder to kidnap"; "A man would be interested in a woman's mind if it bounced gently as she walked"; "Up the bum. No babies!"; "Your thighs won't touch if my head's between them" and "A big legged woman ain't got no soul".
The Chief Censor's effort has also managed a feat which the ministers, Advertising Standards Authority and NZ Transport Agency have not achieved - getting the Australian-based owned of Wicked Campers, John Webb, to defend its actions.
The Chief Censor's decision shows Ford Sumner lawyers were hired and relied on "humour through social commentary" to defend the slogans.
The submission from the law firm to the Chief Censor said the slogans "attract and reflects Wicked's young customer base through its extensive use of popular culture touchstones".
Wicked Campers said it would be an unreasonable limitation on freedom of expression to rule against the slogans when "painting a vehicle with artistic imagery and provocative phrases is no different from an individual displaying artwork in a gallery".
The Chief Censor's ruling said the three vans - which were identified by registration number and slogan - "promote and encourage criminal acts".
While saying the material was shown in a humorous way, there was concern it would attract children and teenagers who might then see the displayed drug use as "funny and cool".
Freedom of speech was also considered but the ruling said the overwhelming balance fell against open publication. The ruling found the slogans were R16 content - then invited Wicked Campers to raise the issue again if it found a way to display the content without those under 16 years of age seeing it.
The ruling by the Chief Censor came after Ms Bennett and two other Cabinet ministers - Louise Upston and Maggie Barry - told the Herald on Sunday they were determined to remove the offensive slogans from the road. Their efforts followed that of National's Dr Shane Reti, whose Whangarei electorate sees many of the vans passing through as tourists travel north.
The politicians' objections have been backed by action from the tourism sector with campgrounds announcing bans on campers carrying offensive slogans.
The Department of Conservation has also removed the company from its website. Protest against the company has spread further with Z service stations polling customers to ask whether they should refuse Wicked Campers service.