Simon Thomas was born on 26 January 1973 in Norwich, Norfolk, England. He spent his early childhood in the small town of Cromer before moving with his family to Grimston. He was raised by his parents Andrew and Gill Thomas, and has two sisters, Hannah and Rebecca. Born to a vicar father, Thomas developed an early interest in broadcasting through work at a Christian centre in the region.

Simon attended Grimston Primary and Middle School before his family relocated to Surrey, where he studied at Aberdour School in Tadworth and later St John’s School, Leatherhead. He then pursued his passion at the University of Birmingham, earning a BA Honours degree in History. After graduating, he worked as a runner at Children’s BBC and at radio station LBC before applying three times for Blue Peter and finally being accepted.

Thomas began presenting Blue Peter on 8 January 1999, replacing the sacked presenter Richard Bacon. During his six years, he ran the London Marathon twice and two Great North Runs, climbed Mount Kilimanjaro and Mont Blanc, completed over 40 solo skydives with the Royal Air Force, presented a medal at the Commonwealth Games, and presented Queen Elizabeth II with a Gold Blue Peter Badge.

He transitioned to Sky Sports in June 2005, initially anchoring the afternoon slot on Sky Sports News. He covered major sporting events including the 2010 FIFA World Cup, the 2010 Ryder Cup, and the London 2012 Olympics. He later became lead presenter for live Premier League football from the 2016–17 season. After stepping back from his career, he returned to Amazon Prime Video in 2020 and rejoined Sky Sports as the host of Soccer Saturday from the 2023/24 season.

His first wife Gemma died suddenly in 2017, just three days after being diagnosed with acute myeloid leukaemia. Thomas married his second wife, Derrina Jebb, in 2021. They had a daughter in 2022 and a son in 2024. The family live in Buckinghamshire.