McKenna has written and produced books and multimedia products, hosted self-improvement television shows and presents seminars in hypnosis, neuro-linguistic programming, weight loss, motivation and the Zen meditation Big Mind.
McKenna started off in radio aged 16 at Radio Topshop, and went on to present for stations including Radio Jackie, Radio Caroline, Chiltern Radio, Capital Radio, BBC Radio One and TV channel Music Box.
McKenna became interested in hypnotism as a result of a guest who appeared hypnotist on his show. His interest stemmed initially for reasons of self-development, although entertainment was later to play a big part. Whilst still working at Capital Radio, McKenna began experimenting with small hypnotic shows, first for the amusement of friends, then for audiences in pubs and clubs. From there he starred in a regular Sunday night show at the Duke of York's Theatre, which was owned at the time by Capital Radio. The success of those shows led to his playing other theatres across the UK, Ireland, The Netherlands, the US, Australia and Hong Kong.
After a brief spell at Radio 1 in the early 1990s, McKenna decided to quit radio. In 1993, ITV broadcast The Hypnotic World of Paul McKenna, which featured audience members volunteering to be hypnotised to act in comedic ways, the show subsequently being aired in 42 countries. During this time, McKenna continued to study hypnosis, and neuro-linguistic programming with Richard Bandler, the co-creator of NLP.
In the 1990s, McKenna presented a number of TV programmes including The Hypnotic World of Paul McKenna (1993–1995), Paul McKenna's Paranormal World (1997) and Hyp the Streets (1999). In January 2008, the Discovery Channel signed a £23 million deal with McKenna to make a series of self-help programmes. To date, the deal is the largest ever for a British TV personality. The first of his I Can Make You Thin programmes aired on TLC, The Learning Channel on 16 March 2008.
McKenna hypnotised Top Gear presenter Richard Hammond on series 4, episode 2 of the motor show in 2004. In October 2009 McKenna was a guest on Private Passions, the biographical music discussion programme on BBC Radio 3.
McKenna has become one of the most successful non-fiction authors in the world with self-help titles including 'I Can Make You Thin', 'Stop Smoking Without Gaining Weight', 'I Can Make You Happy' and 'Hypnotic Gastric Band' included in a wide range of highly popular titles published in countries across the world.
McKenna hypnotised The One Show presenter Matt Baker to believe that he was Pablo Picasso during which time he created several impressionist pieces of art, which were shown on air while the footage was played back during McKenna's appearance on 9 January 2013.
McKenna has also presented several live events including Get The Life You Want with Paul McKenna and Richard Bandler and Get Thin with Paul McKenna.
McKenna attended St Ignatius Secondary School in London and East Hertfordshire College and holds two doctorates; the first from LaSalle University (Louisiana) and the second from the business school International Management Centres Association (IMCA). In 1996, after two years of study on a 70,000-word thesis, McKenna was granted a PhD from LaSalle University. This university was properly licenced by the state of Louisiana, but falsely claimed to be an accredited university. After the principal of LaSalle pleaded guilty to fraud, McKenna, along with thousands of other students was awarded compensation from the U.S. government.
In 2004, McKenna completed an APEL (Accreditation for Prior Experiential Learning) and subsequently gained a properly accredited doctoral degree DPhil from the business school International Management Centres Association (IMCA). The title of his thesis was "The Effects of Fixed Action Patterns and Neuro-Linguistic Programming in Determining Outcomes in Human Behaviour".
In 2006 Paul McKenna successfully sued the Daily Mirror for libel over claims, made by journalist Victor Lewis-Smith, that he had obtained a "bogus degree" merely for money to deliberately defraud the public (the degree was from LaSalle University). McKenna won the case and was awarded substantial damages. The court stated, "Mr McKenna was not, in my judgment, dishonest and, for that matter, whatever one may think of the academic quality of his work, or of the La Salle degree, it would not be accurate to describe it as 'bogus'." Desmond Browne, QC, for McKenna, said that 'any perceived lack of academic rigour at La Salle' did not prove that his client was dishonest.
McKenna has produced self-help books, CDs and DVDs as well as several audio books that provide the information from the books in audible form. In 2006 his book sales alone reached £3.5m. His guides and manuals have been worth just shy of £17m to UK book retailers in the 21st Century, according to Nielsen BookScan data. His book 'I Can Make You Thin' has been called 'The best-selling weight loss book in British history'  with McKenna. His latest book is 'Hypnotic Gastric Band'.
McKenna's full list of published titles include:
- Hypnotic Gastric Band Bantam Press 2013 ISBN 978-0-593-07074-1
- I Can Make You Smarter Bantam Press 2012 ISBN 978-0-593-06405-4
- I Can Make You Happy Bantam Press: 2011 ISBN 978-0-593-06404-7
- Change Your Life in Seven Days - Updated version Bantam Press: 2010 ISBN 978-0-593-06661-4
- I Can Make You Confident, Sterling Publishing: 2010. ISBN 1-4027-6922-9
- I Can Make You Sleep, Bantam Press: 2009. ISBN 1-4027-6574-6
- I Can Make You Rich, Bantam Press: 2007. ISBN 0-593-05537-3
- Quit Smoking Today Without Gaining Weight, Bantam Press: 2007. ISBN 0-593-05536-5
- Instant Confidence, Bantam Press: 2006. ISBN 0-593-05535-7
- I Can Make You Thin, Bantam Press: 2005. ISBN 0-593-05054-1
- Change Your Life in Seven Days, 2005.ISBN 0-593-05053-3
- How to Mend Your Broken Heart, (with Hugh Willbourn) Bantam Press: 2003. ISBN 0-593-05055-X
- The Power to Influence, Nightingale-Conant: 1998. ISBN 1-905453-56-6 (audiobook with Michael Breen)
- The Paranormal World of Paul McKenna, Faber and Faber: 1997. ISBN 0-571-19245-9
- Paul McKenna's Hypnotic Secrets, Boxtree: 1995. ISBN 0-7522-0192-1 (with Peter Willis and Clare Staples)
- The Hypnotic World of Paul McKenna, Faber and Faber: 1994. ISBN 0-571-16802-7
McKenna has also released a number of audio recordings including Sleep Like a Log, Eliminate Stress, "Positive Self-Image", "Attracting Wealth", "Inner Happiness", "Supreme Self-Confidence", Stop Smoking for Good. He also wrote the foreword to Nikolic, Seka and Sarah Tay, You Can Heal Yourself: Bio-energy and the Power of Self-healing.
McKenna learned hypnosis and NLP from Richard Bandler, co-creator of Neuro-Linguistic Programming. He uses Thought Field Therapy in many of his television demonstrations and studied under Roger Callahan, the creator of TFT. He also teaches the Zen meditation 'Big Mind'. He presents the process with its creator, American Zen Master Dennis Genpo Merzel Roshi, abbot and founder of Kanzeon Zen Center in Salt Lake City, Utah.
- 'Look Into My Eyes', The Observer, 12 December 2004
- The Guardian
- The Sun
- The Independent
- BBC Radio 3
- Abstract of thesis Paul McKenna - Website IMCA DPhil dissertations
- Hypnotist McKenna sues over degree claim
- McKenna wins 'fake degree' case
- McKenna the brave Guardian op-ed on McKenna's libel case victory
- Hello Magazine interview
- The Sun
- Sidgwick & Jackson Ltd.: 2006. ISBN 0-283-07038-2
- The Official Paul McKenna website
- Paul McKenna at the Internet Movie Database
- Guardian interview with Paul McKenna
- Hello Magazine interview with Paul McKenna
- The Sun - We Lost Over 13 and a Half Stone with 'Gastric Band' Hypnosis feature with Paul McKenna