Hartnett learned on the job at a hotel in
Cambridge, then at the
Sandy Lane Hotel restaurant in
Barbados. In 1994, she returned to the UK, and undertook a one-day trial at
Gordon Ramsay's first restaurant
Aubergine. Alongside
Marcus Wareing, she worked six days a week alongside Ramsay for longer than the two weeks Wareing predicted – Ramsay called her a bitch occasionally, alongside his favoured name for her: Dizzy Lizzy. In 2004, she gained her first
Michelin star. In 2007, she opened Cielo, a
Ramsay Group restaurant in
Boca Raton. She made her first television appearance in the first series of
ITV1's ''
Hell's Kitchen.'' Murano was awarded a Michelin star and four
AA Rosettes. She created Cafe Murano, a more relaxed setting, in
St James in November 2013 and a further site in
Covent Garden in July 2015. She has since opened 2 more Cafe Murano's in Bermondsey and Marylebone. In 2013 she opened Merchant's Tavern in collaboration with Neil Borthwick and Canteen founders Dominic Lake and Patrick Clayton-Malone. From January to March 2016, Hartnett presented
Tomorrow’s Food alongside
Dara Ó Briain,
Chris Bavin and Dr
Shini Somara. The
BBC One show looks at the
cutting-edge technologies and produce appearing in farms, supermarkets, kitchens and restaurants around the world, and how this is transforming the way we grow, buy and eat our food. In 2020, Hartnett joined Bavin and
Mary Berry as a judge on the BBC One reality cooking show
Best Home Cook, replacing series one judge Dan Doherty. Hartnett was appointed
Member of the Order of the British Empire (MBE) in the
2007 New Year Honours for services to the hospitality industry and
Officer of the Order of the British Empire (OBE) in the
2022 New Year Honours for services to the hospitality industry and to the National Health Service during the
COVID-19 response. For some years she has been a judge for the BBC Food and Farming Awards. One of her fellow judges, journalist
Sheila Dillon, profiled her in "A Life Through Food" on
The Food Programme in January 2022. In 2018 Hartnett was profiled in
Maya Gallus's documentary
The Heat: A Kitchen (R)evolution. In 2022, Hartnett launched the podcast
Dish with television and radio personality
Nick Grimshaw in partnership with
Waitrose. The third Cafe Murano location opened in
Bermondsey in 2019 and a fourth Cafe Murano location opened in
Marylebone in 2025. ==Personal life==