The 57-year-old had a stent fitted after he was taken to a hospital in Solihull.
"Everybody at Birmingham City FC would like to send our best wishes to club legend Trevor Francis following news that he is recovering in hospital from a suspected heart attack," said a club statement.
"The former Blues striker and manager is much loved by everybody associated with the club and we'd like to wish Trevor a speedy recovery."
Francis, who was England's first million-pound player, had complained of severe chest pains on Friday afternoon.
It is believed that the former England international should be allowed to go home with his family next week.
Francis has worked as a pundit since leaving Crystal Palace in 2003.