Ojo averaged 4.1 points and three rebounds in the EuroLeague with Red Star Belgrade.
Former Florida State University center Michael Ojo died on Friday after collapsing during training in Serbia, his former team Red Star Belgrade said. He was 27.
The Nigerian-born basketball player was taken to a hospital in the Serbian capital, but doctors failed to resuscitate him, Belgrade media reported.
"The sudden and shocking death has deeply shaken everyone in the club," Red Star said in a statement.
Ojo was reported to have tested positive for the coronavirus, but also that he had recovered. Local media reported that he died of a heart attack.
After going undrafted in 2017, Ojo moved to Europe where he started his professional basketball career with FMP Belgrade. In 2018, he signed with the regional Adriatic League champions, Red Star Belgrade, where he was hugely popular among the club’s fans.
"Farewell good giant," said a post on a Red Star fan page.
Ojo averaged 6.3 points and 3.3 rebounds in the ABA league and 4.1 points and 3 rebounds in the EuroLeague with Red Star.
The Belgrade club released him at the end of this season and Ojo was believed to be looking for another team in Europe.
The towering 7-feet-1-inch (2.16 m) center wore shoe size 21 and Nike reportedly had to spend $15,000 on a machine to create a size to fit him while he played college basketball in Florida.