Following the final series of Stars in Their Eyes in 2006, Deeley began hosting the reality competition show So You Think You Can Dance in the United States, for which she has been nominated five times for a Primetime Emmy.

[8] At the age of 14, Deeley entered a regional edition of a BBC competition for The Clothes Show, in which she reached the national finals.

Deeley moved on to co-present the MTV chart show, Hitlist UK, with close friend Edith Bowman.

Other programmes she hosted include The Record of the Year, Fame Academy, The 2004 Brit Awards and Stars in Their Eyes, as well as a weekly broadcast on London's Capital FM and a BBC Choice series, Roadtripping, both with former MTV colleague Edith Bowman.

In 2006, Deeley began hosting the second season of American reality show So You Think You Can Dance, replacing newsreader Lauren Sánchez, who was pregnant.

In September 2007, Deeley presented Soundtrack to My Life, a music series produced by Hamma & Glamma Productions for ITV London that looked at the work and influences of an eclectic band of musicians.

[16] Other projects of Deeley's include presenting the third season of Soundtrack to My Life and playing herself as host of comedian Peter Kay's Britain's Got the Pop Factor.

On 9 January 2011, Deeley made a small guest appearance in the Disney Channel sitcom Shake It Up, in which she portrayed a vice principal who is, in secret, a dancer and a host.

In April 2011, Deeley presented an episode of CNN's Icon and spoke to The Simpsons voice actress Nancy Cartwright.

In the same month, Deeley also contributed to the network's coverage of that year's Royal Wedding, which was hosted by tabloid journalist Piers Morgan.

She hosted Fox's celebrity dating game show The Choice, which premiered on 7 June 2012 and ended on 12 July 2012 in the United States.

In 2017, Deeley played Maskface in Ant & Dec's Saturday Night Takeaway miniseries The Missing Crown Jewels.

In October 2017, Deeley began presenting the talent contest Sing: Ultimate A Cappella for Sky One in the United Kingdom.

A Kirkus review of the book concluded "The message is wholehearted and positive, but the cloying execution doesn't stand out.

Her breakthrough as a lead actress came in the 2015 Hulu TV series Deadbeat, playing a celebrity medium named Camomile White.

[28] In June 2024, Deeley came under fire from the Epilepsy Society and viewers of This Morning for making a joke about having a seizure on the show.

[37] During her first few years hosting So You Think You Can Dance, Deeley was described as "an approachable sex symbol" in a Los Angeles Times article published on 4 July 2010.