King was served a trespass letter today by post.
"In accordance with the above Act and section, you are hereby warned to stay off the place known as the parliamentary precincts," the letter read.
In a letter seen by The New Zealand Herald, King has been warned he could face imprisonment or a fine not exceeding $1000.
King was a one-term MP in Northland, elected in 2017 then losing to Willow-Jean Prime by 163 votes in 2020.
He said he was "appalled" to receive the letter.
"It was a trespassed notice for two years and I was pretty appalled by it. I thought it was disgusting and undemocratic and actually pathetic and petty by this Government and [speaker] Trevor Mallard."
While he is unsure if he will challenge the notice, King said he hopes it will be withdrawn due to "media coverage".
"To me, I am campaigning and I am going to be running in the next election and it's going to be a combination of a lot of work."
In February, King addressed anti-vaccine mandate protesters at Parliament. He also revealed at the time he had officially resigned from the National Party, saying its position did not "gel" with his values.
"I would have had to go out and preach their position if I wanted to become a candidate, and I don't want to do that."
During his speech, he urged protesters to remain peaceful and non-violent.
King has often spoken out against the vaccine mandate, and National's support of it.
King, who is now the leader of Democracy New Zealand, said he was planning to launch his new political party on Parliament grounds later this year. But that will now be off the table.
"The irony of Democracy NZ being trespassed from the Parliament grounds, having been a former MP with a clean record and former policemen for 14 years with a clean record ... the irony there alone is just unbelievable.
"I think it was just a brain fart by them [Government] and to me, it's the typical way he [Trevor Mallard] has behaved especially the whole time I have been in Parliament and since then."
King said he was not a leader or organiser for the protest but rather a supporter and is adamant he did nothing wrong.
"I was in support of them because I truly believe in body autonomy and the right to decide so I was solidly behind people that are involved," he said.
"I still am [a supporter] and I will be and I will go to my grave with that."
Other high-profile New Zealanders who attended the protest earlier this year included former deputy prime minister and leader of NZ First Winston Peters, sailing great Sir Russell Coutts, reality star Gilda Kirkpatrick and musician Jason Kerrison.
Winston Peters said his maskless visit to Parliament grounds was to meet the protesters to encourage them to demand that they be heard.
"It's astonishing that on the 16th day no one has opened the dialogue from Parliament from any political party, hasn't been to see them and that's utterly unprecedented," he said at the time.
Although Coutts is fully vaccinated, he said his motivation for travelling to the capital was the fact mandates take away freedoms. He said he was doing this for the "future generations".
In March, the former leader of the New Conservatives, Leighton Baker, pleaded not guilty to charges arising from his participation in the Wellington protest.
But the prominent anti-mandate protester didn't need to enter the courtroom to make his plea.
Baker (55) faces charges of obstructing police and wilful trespass after he was arrested at the occupation that spanned 23 days before erupting into a riot on the front lawn of Parliament.
