Mulhern began his television career with CITV in 1998, presenting shows such as Finger Tips, Tricky TV and Holly & Stephen's Saturday Showdown until 2007, when he got his big break presenting the ITV2 spin-off show Britain's Got More Talent, airing immediately after the main ITV show, which is hosted by Ant and Dec. Stephen has hosted all series of the spin-off show to date.
He made his Saturday night debut on ITV, when he hosted the game show Magic Numbers for eight episodes in 2010, and has since presented Catchphrase, Big Star's Little Star and In For a Penny, all for ITV. In 2024, Stephen would reunite with his Saturday Showdown co-host Holly Willoughby to present ITV's Dancing On Ice.
In addition to his primetime roles, Stephen has presented the ITV daytime programme This Morning as a guest presenter and 'Hub' anchor, reading out viewer comments about topical issues for discussions. Stephen has also narrated Clip Show (blank) Do the Funniest Things and presented the ITV primetime show Anonymous. However, these shows are not currently airing. Stephen currently hosts a radio programme on Heart, alongside Emma Willis.
Shows he presents or has presented:
- The Quick Trick Show
- Finger Tips (Co-presenter)
- You Can Do Magic
- SMTV Live
- Globo Loco
- The Record of the Year
- Holly & Stephen's Saturday Showdown (Co-presenter)
- Tricky TV
- Dancing on Ice: Defrosted
- Britain's Got More Talent
- All Star Impression Show
- Anonymous
- Animals Do the Funniest Things
- Magic Numbers
- Coronation Street Uncovered: Live
- The 5 O'Clock Show
- The Big Quiz
- This Morning (occasional Stand-in Presnter)
- This Morning's Hub
- Emmerdale Live - The Fallout
- All Star Mr & Mrs: Text Santa Special
- Catchphrase
- Big Star's Little Star
- Sunday Side Up
- The Paul O'Grady Show (Guest Presenter)
- The Illusionists
- In For a Penny
- Deal or No Deal (2023 revival)
