From 1977–80, he worked for the investment banksLehman Brothers and Lazard Frères in New York, training as an investment banker, and qualified as a barrister in 1976, becoming a member of Gray's Inn. He was seconded to the British Steel Corporation to work with Sir Ian MacGregor. He was appointed Managing director of British Steel Service Centres Ltd and later appointed Commercial Director British Steel, establishing joint ventures in China, Turkey, Europe and North America. After British Steel, he managed a number of private steel and manufacturing businesses. He was elected as MP for North Norfolk in 1997 and he became Chief Executive of the Conservative Party and its deputy chairman and a member of the trade and industry select committee. In 2002 he was appointed chairman of the Norfolk and Norwich University Hospital NHS Trust, resigning in November 2006. He was acting chairman of the Conservative Party in 2001. On 14 November 2006, he was arrested, among others, by Norfolk Constabulary investigating allegations of financial irregularities at Cawston Park Hospital previously known as Cawston College, a private psychiatric hospital in Cawston, Norfolk. He was cleared of involvement in the alleged fraud on 15 February 2007 and subsequently reappointed as chairman of the Norfolk and Norwich University Hospital NHS Trust. In 2009, he was invited to be Chairman of Ormiston Victory Academy in Norwich. He founded and chairs two free schools, the , and Sir Isaac NewtonFree School, a sixth-form college specialising in sciences and mathematics. He is also the chairman of Norwich Primary Academy. In 2012, he became a Trustee of the Inspiration Trust. From 2005-2009 he was Chairman of Friends of Families House. On 28 January 2013 he was appointed as Chairman of the Care Quality Commission. He was said by the Health Service Journal to be the 23rd most powerful person in the English NHS in December 2013. In April 2014 he had a hip replacement operation paid for by private insurance but was treated in a public ward at the Norfolk and Norwich University Hospital NHS Trust. In March 2015 he told a conference that "the role of the market is hugely limited in health and social care, in part because many of the people who need care the most – as many homeless people are – are often unheard; they have no power. The market requires people with power, people who can choose . In healthcare that’s not the case.” His stance appeared to conflict with the assumptions underlying the Health and Social Care Act 2012. On 14 May 2015 David Prior was appointed Parliamentary Under-Secretary of State for Health in David Cameron's Conservative ministry and subsequently created a Life Peer as Baron Prior of Brampton, of Swannington in the County of Norfolk on 29 May 2015. He was reckoned by the Health Service Journal to be the twelfth most influential person in the English NHS in 2015. In October 2016, Prior said the result of the 2016 United Kingdom European Union membership referendum was "a terrible mistake". Additionally, he expressed his support for remaining in the European single market. On 21 December 2016, he was appointed as Parliamentary Under Secretary of State at the Department for Business, Energy and Industrial Strategy. A large part of this role was the development of the Government's new industrial strategy. He resigned from the Government in October 2017. On 5 September 2018, he was invited to attend a pre-appointment hearing with the Health Select Committee prior to being appointed , succeeding Sir Malcolm Grant. His appointment was for four years from 31 October 2018.