The Brazilian-born player, who played twice for Stoke's first team after spending three years at the club, is believed to have passed away after a heart attack in his native country.
Teixeira joined Moldovan Sheriff Tiraspol side in February this year and made 10 appearances as Sheriff won the Moldovan National Division title. Teixeira also played for Kosice, Slovan Bratislava, Banik Ruzina and Dukla Banska Bystrica and made eight appearances for Fleetwood Town during a loan spell from Stoke in 2015.
A statement on Stoke's website read: 'Stoke City extends sincere condolences to the family of former defender Dionatan Teixeira following his untimely passing at the age of 25. Chief executive Tony Scholes added: 'Dionatan was a hugely popular member of our squad and it's difficult to comprehend that he has passed away at such a young age.
'Our thoughts and prayers go out to his young family and friends at such a difficult time.'
During his time in England, Teixeira also played for Fleetwood Town, who also released a statement expressing their sadness at his passing.
The League One side said: 'The thoughts of everyone at #ftfc are with the family and friends of former player Dionatan Teixeira, who has sadly passed away aged 25.'
A statement on the Sheriff Tiraspol website said Teixeira had travelled to his native Brazil in the summer and had been due to return to the club.
The Sheriff Tiraspol statement read: 'A few hours ago, a good man and an excellent football player, former FC Sheriff player Dionatan Teixeira died.
'The Brazilian defender was only 25 years old. The whole of the club is shocked by this tragic news. The pain of loss is great.