Messenger, who had worked as an electrician both in the RAAF and through his own small business was chosen by the National Party to re-take the traditional safe seat of Burnett in the 2004 Queensland election. Burnett had been lost to the ALP in the 2001 Queensland state election. Messenger succeeded in winning Burnett from the Labor candidate Trevor Strong, managing a swing of 4.3 per cent.
He was re-elected in 2006 with an additional swing of 4.7 per cent.
In 2005 Messenger was approached by Toni Hoffman, an experienced surgical nurse, distressed about one of the surgeons at the Bundaberg Base Hospital where she worked. She had previously consulted with hospital management with no success.
As a result of a long discussion with Hoffman, he named Jayant Patel under Parliamentary privilege. Messenger first raised the matter in Parliament on 22 March 2005, for the protection of patients at the Bundaberg Base Hospital intensive care unit and the wellbeing of the medical staff.
Shortly afterwards it was discovered by Courier Mail journalist Hedley Thomas that Patel had previously been charged with misconduct in the United States.
Patel's activities subsequently came into the public arena and he eventually became the central figure in the "Dr. Death" scandal which resulted in a Commission of Inquiry.
On 8 February 2007 Messenger was censured by the Queensland Parliament for a sarcastic comment made to the Premier over the scandal.
In May 2010, Messenger and Beaudesert MP Aidan McLindon resigned from the LNP to sit as Independents, claiming that the party had become victim to "flawed political process". Shortly afterwards it was revealed Messenger and McLindon were under party scrutiny, with Messenger's travel claims raising some concerns. Messenger denied that he had done anything wrong and called upon the LNP president Bruce McIvor to resign.
Messenger has campaigned for a sex offenders register that would allow parents to protect their children from known sexual offenders.
In June 2011, Messenger indicated interest in joining the newly formed Katter's Australian Party if his policy demands were met, including a ban on Sharia law in Australia, and an increase in military numbers.
Messenger lost his seat at the 2012 state election to his former party.
In May 2013, Messenger joined the Palmer United Party (then called the United Australia Party) and was announced as its first federal candidate, contesting the seat of Hinkler. He won 17.65% of the vote, coming third behind the LNP and Labor candidates. In April 2014 he was appointed chief of staff to incoming Palmer United senator Jacqui Lambie of Tasmania. Following tensions between Clive Palmer and Jacqui Lambie, he was expelled from the party in November 2014.