In his seven years at United the Ivory Coast player made over 150 appearances, including three last season.
He joined Chinese second-tier side Beijing Enterprises in February.
"It is with deep sadness I confirm that Cheick Tiote sadly passed away earlier today after collapsing in training," said spokesman Emanuele Palladino.
"We cannot say any more at the moment and we request that his family's privacy be respected at this difficult time. We ask for all your prayers."
In February 2011, he scored a memorable goal as Newcastle United came back from 4-0 down to draw with Arsenal in the Premier League.
He joined Beijing Enterprises Group FC for an undisclosed fee in February 2017.
