Member for Buderim Steve Dickson, who served as racing minister in the Newman government until 2015, announced on Friday that he was ditching the LNP to join One Nation.

It will be the first time the Queensland Parliament has had a sitting One Nation MP in eight years.

It comes after denials from Mr Dickson that he was planning to join Pauline Hanson, despite inviting the One Nation leader to his electorate in October.

Mr Dickson said his decision to abandon those he sat alongside in state politics for a decade was due to his passion for an amnesty for parents who provide medicinal cannabis to their children.

"I'm putting my career on the line today," Mr Dickson said.

"[I] believe that the major parties have lost their way.

"I've also emailed all of my parliamentary colleagues and I say to all of them, I'm not the enemy. I'm going to work with you, I want the Queensland Parliament to be much more bipartisan."

But LNP insiders played down the significance of medicinal cannabis, suggesting the Sunshine Coast MP's decision was more about his "career prospects".

Mr Dickson was involved in a failed coup to install LNP MP Tim Mander as leader in early 2016 and missed out on a shadow ministry in the Tim Nicholls opposition.

But Mr Dickson is likely to be a powerbroker in the One Nation ranks, as one of only a few members with a strong political background.

Ms Hanson did not rule out Mr Dickson becoming the party's leader in Queensland, but said it was yet to be decided.

His former colleagues were said to be upset at his decision, although by making the move in January - potentially many months before a state election is called - it gave the LNP a greater chance of pre-selecting a quality candidate for Buderim.

A high-ranking LNP official said: "There's a special place in hell reserved for rats."

One LNP insider said: "It's a massive betrayal."

Mr Dickson called Opposition Leader Tim Nicholls only 15 minutes before his press conference in Buderim and LNP president Gary Spence only moments beforehand, sending a brief email advising he was quitting the party.

There were some mixed emotions within the LNP, and while the defection came at short notice, it was not necessarily surprising to all that he left for One Nation.

Mr Spence labelled Mr Dickson's decision a "betrayal about self-interest".

"Steve Dickson has broken his word and the personal assurances that he made to the LNP that he would not be leaving the party," Mr Spence said.

Mr Nicholls abandoned his holiday on Friday afternoon to speak to journalists, alongside his deputy Deb Frecklington, and appeared to be trying to remain measured in his anger.

"This is simply about Steve's own political self-interest," Mr Nicholls said.

"I'm disappointed, I think the people of Buderim will be disappointed, I think his colleagues in the LNP who have supported him for the past decade will be disappointed."

Mr Nicholls said he was not worried about other members in his ranks defecting to One Nation, after being asked whether he thought member for Cleveland Mark Robinson could be the next to go.

He described Mr Robinson as a "solid supporter of the LNP" who would continue to be a party room member.

Mr Robinson posted a photo on Facebook in December, describing how it was good to meet with Ms Hanson and Mr Dickson to "chat about our great state that we all love. Interesting times ahead with Pauline [Hanson]".

But on Friday afternoon, Mr Robinson stated he had no plans to leave the LNP.

"Today my colleague & good friend Steve Dickson MP left the LNP... & joined Pauline Hanson's One Nation. People are asking if I am going too?" Mr Robinson wrote on Facebook.

"The answer is that I have no plans to follow.

"I plan to remain with LNPQld while-ever the LNP is loyal to those good values that my community supports.

It is understood the party was investigating an allegation that Mr Dickson downloaded internal documents on Thursday which were designed for LNP candidates and MPs ahead of the upcoming election.

By Friday afternoon, the LNP had already opened nominations to find a new candidate for Buderim.

The electorate of Buderim is considered a safe LNP seat, with Mr Dickson receiving 62 per cent of the two candidate preferred votes after preferences, holding the seat on a 12 per cent margin.

With a One Nation MP in Queensland's hung parliament, the house is set to become even more interesting when sitting resumes on Valentine's Day.

Labor will have the benefit of gaining a one-seat lead on the LNP, but the government will need to negotiate with an increasingly complicated crossbench to get legislation passed.

The count is now: 42 Labor, 41 LNP, while the crossbench features Robbie Katter and Shane Knuth with Katter's Australian Party, independents Rob Pyne, Billy Gordon, Peter Wellington and Steve Dickson with One Nation.

However, while others doubted Mr Dickson's motivations on medicinal cannabis, Mr Pyne said the new One Nation MP was passionate about the cause.

"He's not making this up, he's got a real commitment to cannabis, as have I," Mr Pyne said.

"I can't see why people can't have access to the whole of the plant to use for their own medical or physical reasons.

"Many of my friends in wheelchairs use cannabis - it gets good results in muscle spasms.

"[But] I don't agree with him in terms of One Nation."

A state election is due by early 2018.