Colbeck was born in Myrtleford, Victoria, and was educated at Devonport Technical College. He was a building estimator and supervisor, managing director and proprietor of a building consultancy before entering politics. In his early years, Colbeck gained qualifications in Small Business Management; Technology ; and Carpentry and Joinery Trade and Proficiency. He was an apprentice carpenter and joiner between 1977–79; a trainee estimator and supervisor 1977–79; and manager 1979–84. Between 1984 and 1989 he was a building estimator and supervisor; and managing director and proprietor of building consultancy from 1989. From 1993–1996, and from 1998–2000, Colbeck served as the president of the Devonport Chamber of Commerce. From 1998–2001, he was a member of the Board of Directors of the Tasmanian Chamber of Commerce and Industry. From 1999–2002, he was an Alderman of the Devonport City Council.
Political career
On 4 February 2002, Colbeck was appointed to the Senate by the Governor of Tasmania under section 15 of the Constitution, to fill the casual vacancy caused by the retirement of Senator Jocelyn Newman. He had already been elected to the Senate at the 2001 federal election, to a term beginning on 1 July 2002. He was re-elected in 2007. Colbeck was appointed Parliamentary Secretary to the Minister for Agriculture, Fisheries and Forestry in October 2004. In January 2006 he was appointed Parliamentary Secretary to the Minister for Finance and Administration. With the defeat of the government led by John Howard in 2007, he was appointed to the shadow ministry as Shadow Parliamentary Secretary for Health. He was shifted to the role of Shadow Parliamentary Secretary for Agriculture, Fisheries and Forestry in September 2008. In September 2010, Colbeck was appointed Shadow Parliamentary Secretary for Fisheries and Forestry and Shadow Parliamentary Secretary for Innovation, Industry and Science by the new opposition leaderTony Abbott. Abbott nominated Colbeck for appointment to the Abbott Ministry as the Parliamentary Secretary to the Minister for Agriculture following the 2013 federal election. Following the 2015 leadership spill that saw Malcolm Turnbull replace Abbott as prime minister, Colbeck was appointed as the Minister Assisting the Minister for Trade and Investment and the Minister for Tourism and International Education in the First Turnbull Ministry from September 2015 to July 2016. At the 2016 federal election, Colbeck was demoted to fifth place on the Liberal Senate ticket. He blamed factional opponent Eric Abetz for his failure to win a higher position on the ticket. He polled an unusually high below-the-line tally, attributed to a strong "personal vote", but nonetheless lost his seat. Colbeck unexpectedly returned to the Senate in February 2018, after Senate President Stephen Parry was caught up in the parliamentary eligibility crisis. The Court of Disputed Returns conducted a recount and declared Colbeck elected. Colbeck is considered to belong to the moderate wing of the Tasmanian Liberals, and supported Malcolm Turnbull during the 2018 leadership spills; he was reportedly the only Tasmanian Liberal not to sign the petition calling for a second spill. In the new Morrison Government, he was appointed Assistant Minister for Agriculture and Water Resources. Prior to the 2019 federal election he was preselected in first place on the Liberals' Senate ticket.