After attending Auckland Grammar School where he was Head Prefect in 1984, Coleman trained as a doctor, graduating from University of Auckland's medical school. He worked as a doctor in New Zealand, the United Kingdom, and Australia. He later obtained an MBA from London Business School in 2000, and returned to New Zealand the following year. He worked for PricewaterhouseCoopers as consultant on health sector issues and as a part-time general practitioner in Otara. He entered the selection for the National Party candidacy for Tamaki but was defeated by Allan Peachey before successfully contesting the candidacy for Northcote. He has a 170-year family connection to his Northcote electorate and “a bit of tangata whenua thrown in” to his bloodline.
In the 2005 election, Coleman stood as the National Party's candidate for the Northcote seat. He was also ranked 35th on the party's list. Coleman was successful, defeating Ann Hartley of the Labour Party. This was the only Auckland seat to change hands between Labour and National in the 2005 election. In 2006, Coleman caused controversy when he accepted British American Tobacco's – an active lobbier on health sector issues – offer of sitting in their corporate box during a U2 concert. It was alleged he blew cigar smoke at a woman during the concert. Coleman admitted he made a mistake by sitting in British American Tobacco's corporate box and smoking at a U2 concert. In the Coleman was re-elected in Northcote with a majority of 9,360 votes. He was again successful in the, winning by a majority of 9,379 votes. He had a slightly increased majority in the.
2011–14
After being re-elected for a third term for the Northcote seat in November 2011, Coleman was promoted in Cabinet to Minister of Defence, Minister of State Services and Associate Minister of Finance. In 2012, Coleman made a secret visit to Afghanistan to visit New Zealand troops. Coleman said the visit was a "chance for him to offer his support to the troops for the important work they were doing providing security in the province". As Minister of Defence, Coleman led the implementation of the 2010 Defence White Paper. He commissioned the Defence Mid-Point Rebalancing Review which set out the long term approach, balancing funding, capabilities and policy. Coleman oversaw the NZDF's successful withdrawal from its three largest missions in Afghanistan, Solomon Islands and Timor-Leste. Coleman voted against the Marriage Amendment Act 2013.
2014–18
In 2014 Coleman became the first doctor in 70 years to take the health portfolio. In May 2015, Coleman described the Young Labour's proposal for freegender reassignment surgery for transgender people in New Zealand as a "nutty idea". On 20 May 2015, a meeting in Alexandra organised by Central Otago Health Services Ltd supported a vote of no confidence in Health Minister Jonathan Coleman. When Russell Garbutt moved a motion of no confidence in the minister and emailed him the following morning, he did not expect Coleman to pick up the phone and call . They spoke for more than 10 minutes, with Coleman telling Mr Garbutt the Southern District Health Board was his number 1 priority in respect of its budget woes.
Leadership campaign
Coleman announced his intention to seek the National Party leadership in 2016 after John Key announced his intention to resign. He was unsuccessful, with Bill English becoming the new PM.
