Yohann Diniz (born 1 January 1978 in Épernay) is a French race walker.
He won the gold medal in the 50 km race at the 2006 European Championships in a personal best time of 3:41:39 hours. He then repeated the feat at the 2010 European Championships in a personal best time of 3:40:37 hours.
In 2007 Diniz won the European Race Walking Cup at Royal Leamington Spa with a French record time of 1:18.58 hours. He then won the silver medal in the 50 km race at the 2007 World Championships.
At the 2008 Summer Olympics in Beijing on an extremely humid day, Diniz was forced to withdraw from the 50km walking race after about 30km from the starting line because of pain in the stomach and thigh.
In 2009, he achieved the world's best performance for the 50km walk - 3hr 38 min 45 sec.
He set a world record time of 3:35:27 in the 50,000 metres track walk in March 2011, defeating Thierry Toutain's previous world mark, set in 2000, by more than five minutes.
At 2011 IAAF World Championships in Daegu, Diniz was disqualified from the 50km walk for three red cards.
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.
At the 2012 Summer Olympics in London, Diniz was disqualified from the 50km walk immediately after his arrival at the finish line in eighth position for taking a bottle of water at the 38th kilometer mark outside a zone provided for water replenishments.