[5] In his teens Denny turned his attention to athletics and built a homemade discus circle on his family's rural property.

[citation needed] Denny represented his country in the discus at the 2016 Summer Olympics in Rio de Janeiro without qualifying for the final.

In June 2021 on the Gold Coast, Queensland he qualified with a 68 cm personal best of 66.15m which moved him from fifth to third Australian all-time.

[5] Denny qualified for the Tokyo 2020 Olympics and competed in the final having thrown 65.13 m in his Men's discus throw qualification.

[9] Denny threw a meeting record 69.96m to win the 2024 Diamond League final in Brussels, Belgium.