Iolo Tudur Williams was born on 22 August 1962 in Builth Wells, Breconshire. His family moved to Pembrokeshire before relocating to Montgomeryshire when he was aged five, to live in Llanwddyn near Lake Vyrnwy. His father, Dai Williams, was a school headteacher, and his mother is Megan Williams. He has a sister named Ffion.

Educated at Llanfyllin High School, after gaining two A-Levels in Biology and French, he almost joined the British Army but instead went to the North East London Polytechnic (now the University of East London), graduating with a degree in Ecology. His role as Species Officer for Wales saw him work with some of the country’s rarest breeding birds and this, inevitably, brought him to the attention of the media, making a name for himself as a leading expert on Welsh bird life.

In 1997, Iolo teamed up with BBC Wales to make his first TV programme, Visions of Snowdonia. After making a second series, he left the RSPB in 1999 to pursue a full-time career in the media. In 2019, Williams became a regular presenter on Winterwatch, Springwatch and Autumnwatch on BBC Two and hosts other popular shows including, lolo River Valleys.

Iolo Williams is married to Ceri. The couple resides near the town of Newtown, Powys, with their two sons, Dewi and Tomos, and two rescue dogs, Ianto and Gwen. They love growing their own vegetables and composting their food waste.