Dinham was born in South Africa and lived there until he was 11.[1] He started riding at the age of four, trying most of the other disciplines of cycling before settling on road. Dinham became an Australia citizen in 2017 a few weeks before he represented Australia at the UCI Mountain Bike World Championships[1]
Dinam was a last minute call up for the Road race at the 2023 UCI Road World Championships after Caleb Ewan decided not to race.[8][9] The race plan for Dinham involved going into the early break and take some of the pressure off Michael Matthews. But Matthews dropped out of contention so Dinham took it upon himself to get a good placing. When the favorites caught his breakaway, Mathieu van der Poel attacked. Dinham was the only rider from the break to be able to follow, he joined the likes of Wout van Aert and Tadej Pogačar. Van der Poel kept attacking and the bunch split into groups with Dinham being in the bunch that sprinted for fifth where he finished seventh.[9][10]
^ abcBeen, José (31 October 2022). "Meet Matt Dinham, the Aussie climber joining the WorldTour ranks". velo.outsideonline.com. Retrieved 7 October 2023. Dinham spent his early childhood in South Africa where both his parents plus he and his sister were born. He tried many different cycling disciplines like BMX, downhill, and cross country mountain biking because he just wanted to race. When Dinham was 11 years old, the family moved to Australia.