In 2007 Diniz won the European Race Walking Cup at Royal Leamington Spa with a French record time of 1:18.58 hours.

[2] Diniz improved his 20 km walk time to 1:17:43 hours at the Memorial Mario Albisetti in March 2012, placing second behind Alex Schwazer.

In July 2015, Diniz announced his withdrawal from the upcoming 2015 World Championships in Athletics because of persistent pain in his inguinal ligament that would result in him undergoing an operation soon.

[6] At the 2016 Summer Olympics he led the race, but due to gastrointestinal issues, he fainted multiple times midrace.

[citation needed] In 2019, he competed in the men's 50 kilometres walk at the 2019 World Athletics Championships held in Doha, Qatar.