Iain Andrew Stirling was born on 27 January 1988 in Edinburgh, Scotland, to parents Alison and Rodger Stirling, and grew up alongside his sister, Kirsten. He attended Liberton High School before studying Law (LLB) at the University of Edinburgh, where in his final year he began stand-up comedy, reaching the final of the Chortle Student Comedian of the Year competition in 2009 (runner-up to Joe Lycett).

After being spotted at a gig, Stirling became a lead presenter on the CBBC Channel alongside his sidekick Hacker T Dog, later hosting the panel show The Dog Ate My Homework, for which he received a BAFTA nomination in 2014. In June 2015 he became the narrator of ITV2’s Love Island, a role he has held for every series since, later extending to Love Island USA on Peacock from 2022.

He co-created and starred in the ITV2 sitcom Buffering (2021–2023), was runner-up on Taskmaster series 8 (2019), and won the Celebrity MasterChef: Christmas Cook-Off in December 2025. In August 2026, he began hosting Race Against the Tide, a BBC Two/BBC Scotland sand-sculpting competition filmed on West Sands Beach in St Andrews.

Stirling married fellow presenter Laura Whitmore in 2020 in a humanist ceremony at Dublin City Hall; their daughter Stevie Ré was born in March 2021.