Duncan is best known for being one quarter of Blue, the pop group, which was born in 2001.
 
They exploded onto the scene and amassed huge commercial success, racking up 40 Number One singles worldwide, three Number One UK albums and sales of over 16 million records.
 
In 2005 the guys decided to take a break and Duncan starred as Billy Flynn in the hit musical Chicago. He also competed in ITV's Dancing On Ice in 2007 where he became a finalist, and participated in the subsequent sell-out tour in arenas across the UK.

2011 saw the Blue boys come 11th representing the UK at the Eurovision Song Contest in Düsseldorf with "I Can".
  
Duncan went on to play the role of Ryan in the popular Channel 4 soap opera Hollyoaks. He was nominated for Most Popular Newcomer for the 2016 NTA's Best Newcomer for the 2017 Soap Awards.

Further TV appearances have included: Grease: The School Musical for Sky 1, Eurovision: Your Country Needs You (Judge) for BBC1, Eight Out Of Ten Cats for Channel 4, Don't Stop Believing (Judge), Blue Goes Mad In Ibiza for ITV2, 2020’s The Circle, 2021’s Celebrity Masterchef and Strictly The Real Full Monty; The Weakest Link; Emily Atack Show; Ch4 Jon & Lucy’s Couple’s Therapy; Celebrity Gogglebox with his best friend, Denise van Outen.

Presenting credits include: The National Lottery, Scream If You Know The Answer, Soapstar Superstar, Capital FM's Party In The Park, City Hospital, T4, The Clothes Show and GMTV’s Entertainment Today.

Theatre credits include: Legally Blonde West End (Warner Huntington III), Priscilla Queen of the Desert UK Tour (Tick), The Rocky Horror Show UK Tour (Frank-N-Furter), Jeff Wayne’s Musical Version of The War of The Worlds Arena Tour (Parson Nathaniel)
 
In 2020/21 Duncan was the resident headliner for Proud Cabaret in London’s West End.

In 2023 Duncan returned to presenting for Good Morning Britain as a regular Entertainment reporter. He also won the Celebrity Masterchef Christmas Cook Off.

He made his pantomime debut in 2014/15 playing the title role in Jack and the Beanstalk at the Birmingham Hippodrome. He then starred as Prince Charming in Cinderella at the Liverpool Empire in 2017/2018, Aladdin at White Rock Hastings in 2019/2020, Jack in Jack & The Beanstalk at Marlowe Theatre, Canterbury 2021/2022 and Daston in Beauty and the Beast at Sheffield Lyceum 2023/24.

Instagram - @mrduncanjames