Ritchie's promoter confirmed the boxer's death in a Facebook post.
"It is with great sadness and shock to announce that the fighting cowboy Dwight Ritchie sadly passed away today doing what he loved," Jake Ellis wrote.
"As Dwight's promoter and friend it's unbearable to accept the tragic news that's just surfaced."
Mayweather fails to knock out YouTuber Logan Paul in eight rounds
07/06/2021 AT 08:05
One of the country's brightest boxing talents, Ritchie last fought Tim Tszyu, the son of former world champion boxer Kostya Tszyu, in August for the IBF Australasian super welterweight title in Sydney.
He lost by unanimous decision but was to return to the ring next month for a light-middleweight fight against Tommy Browne.
Sydney's Daily Telegraph newspaper reported that Aboriginal Australian Ritchie, who had a record of 19 wins and two defeats, collapsed when sparring with another boxer in Melbourne on Saturday and could not be revived.
Ritchie leaves three children behind.
His death sparked a flood of tributes from local boxers on social media.
"Today we lost one of our own," Australian professional and Olympian Luke Jackson wrote on Twitter.
"I remember having my professional debut on Dwight’s card. Sending my love to his family, loved ones and the whole of boxing Australia."
(Reporting by Ian Ransom; Editing by Daniel Wallis)
Tokyo 2020
‘Let’s complete the journey’ - Clarke on Olympic boxing dream
04/06/2021 AT 13:24
Tokyo 2020
Price bidding to follow in Adams' footsteps ahead of Tokyo debut
27/05/2021 AT 14:00