In 2005 O'Dea was the general manager of the Crown Insurance Group and a director with HCF and was named as a potential candidate for the seat of Pittwater, following the resignation of the sitting member and Opposition leader, John Brogden. However, O'Dea did not stand. In a Liberal Party preselection battle before the 2007 state election, O'Dea defeated the sitting member for Davidson, Andrew Humpherson. Humpherson had cross-factional backing among many delegates, but had lost support in local branches after reportedly instructing party members to quit branches supportive of O'Dea, thereby reducing their voting power. Despite Humpherson having the support of the Party Leader, Peter Debnam, O'Dea won the vote 54 votes to 52 and Humpherson chose to not re-contest the election. In March 2007, O'Dea was elected to Parliament with a majority of 24.7 points. In June 2007, he was appointed a member of the Committee on the Independent Commission Against Corruption. From 2008 in Opposition, O'Dea served as the chair of the NSW Coalition WasteWatch Committee. In 2011 he was elected Chair of the crucial cross-party Public Accounts Committee of the NSW Parliament. In September 2009, O'Dea was accused in a local newspaper, the Manly Daily, of failing to adequately represent his constituents, by Ku Ring Gai Councillor Tony Hall, who urged O'Dea to "get off his backside" and lobby New South Wales Planning Minister Kristina Keneally to protect the area from excessive development. O'Dea responded, defending his record: "Along with Barry O'Farrell I have fought long and hard against inappropriate planning and over development...in the past 12 months I have taken part in 30 formal meetings with authorities and community representatives regarding Ku-ring-gai planning matters, three involved the planning minister and community representatives". On 18 October 2010, the Liberal Party announced that O'Dea had been endorsed as the party's candidate for Davidson ahead of the 2011 State election. O'Dea was elected with a swing of 13.8 per cent and won the seat with 86.5 per cent of the vote on a two party preferred basis. His main competitor was Labor's Mathew Gilliland. In 2015 O'Dea was re-elected with 78.8 per cent of the vote on a two party preferred basis, a swing 4.1 per cent against him, defeating the Green's David Sentinella. In 2019 O'Dea was again re-elected with 75.2 per cent of the vote on a two party preferred basis, a swing 3.7 per cent against him, defeating the Green's Felicity Davis. On 28 March 2015, O'Dea was appointed as Parliamentary Secretary for Tourism and Major Events. In April 2016, Premier Baird conferred the additional title of Parliamentary Secretary for Trade and Investment. After the change in Premier to Gladys Berejiklian he was appointed Parliamentary Secretary to the Premier and Treasurer. At the 2019 state election, O'Dea suffered a small swing against him, but was still reelected with a majority of 75.2 percent against the Greens, making Davidson the safest Liberal seat in Sydney. Following the election, Premier Berejiklian nominated Mr O'Dea as the 40th Speaker of the Legislative Assembly, succeeding Shelley Hancock. The NSW Parliament Legislative Assembly subsequently elected Mr O'Dea as Speaker on 7 May 2019. In line with established parliamentary tradition, Mr O'Dea was ceremonially ‘dragged’ to the Speaker's chair by Premier Berejiklian and Planning Minister, Rob Stokes.
Personal life
O'Dea resides in the suburb of Lindfield with his wife Jacqueline and their four children.
