Jarque passed away around 8pm local time when his heart stopped following a training session in Coverciano, Italy, where the squad are on a pre-season camp.
Immediately after scoring the winning goal, the 26-year-old had taken off his Spain shirt to reveal a white T-shirt bearing the message: "Dani Jarque: always with us".
Jarque's death comes two years after that of Sevilla and Spain defender Antonio Puerta, who suffered multiple organ failure in hospital, three days after a cardiac arrest during a league match against Getafe.
Reports suggest Jarque was on the phone to his fiancee -- who is eight months pregnant -- at the time and she alerted two of his team-mates, who raced to his hotel room.
"We are all in mourning and I wish to express in the name of FC Barcelona our heartfelt condolences to Espanyol on the painful loss of their captain Dani Jarque, and also to his family".