In the newly created role, Dean will oversee news and showbusiness content on the weekday show. Formerly editor-at-large at the Evening Standard's ES magazine, she reports to programme editor Siubhan Richmond.
Executive producer James Hunt told PRWeek lines between different subject areas on the programme's editorial agenda were increasingly blurred, and that Dean would oversee a team of producers and researchers in a bid to simplify who puts together what feature.
Hunt said: 'Is something a news story, a celebrity story or a human interest story? This is about strengthening the editorial of the programme, making us more efficient.'
On average, 3.1 million people tune into This Morning each day for a mixture of news, health and entertainment slots, plus celebrity interviews.
Hunt said PROs should continue to pitch ideas, particularly in health.
'This Morning is a meaty, family-oriented, female magazine show. We have a positive relationship with PROs and are always on the lookout for ideas and thoughts. Medical advice remains one of the core aspects of This Morning.'
News editor Karen Thorpe left the programme in March, and producer Tim Chilcott has been in charge of the news operation since then.
This Morning was launched 15 years ago and gained wide-spread attention during the 1990s when it was presented by Judy Finnegan and Richard Madeley.
The husband and wife team defected to Channel 4 in 2001 and the ITV1 show lost 400,000 viewers. Abortive attempts to claw back its audience included a brief period with Twiggy as a presenter.
Last October, the programme came under the media spotlight again when Granada terminated the contract of presenter John Leslie, claiming he failed to respond to its questions over allegations against him of sexual assault.
Philip Schofield has presented the show, co-hosted by Fern Britten, since his departure.