The Spanish Football Federation announced the devastating news in a statement the morning after Spain’s historic 1-0 win over England.
“We send our most sincere hugs to Olga and her family in this moment of deep pain,” the federation said.
“We love you, Olga. You are part of the history of Spanish football.”
According to Spanish media, Carmona's father had died in the days leading up to the final but her family had kept the news from her to allow her to focus on the match.
Her mother and brothers flew to Sydney for the final, having returned to Spain after the group stage.
Carmona, a 23-year-old left-back from Real Madrid, was the star of the final, delivering another clutch moment after scoring the winning goal in the last minute of Spain's semifinal victory over Sweden.
She was the first player since United States legend Carli Lloyd in 2015 to score in both the semifinal and final.
Carmona scored the only goal of a high-energy final with a crisp left-footed strike in the 29th minute after making an overlapping run down the wing.
The goal came from a mistake from England’s Barcelona right-back Lucy Bronze, who turned the ball over on halfway, allowing Spain to strike on the counter.
Carmona said Spain's win was still sinking in when she paused her celebrations to front a press conference as the player of the match almost three hours after the fulltime whistle blew.
”The truth is it’s a unique moment and neither myself or my teammates or the staff are fully aware of what we’ve done, but I think we will be when we land in Spain,” Carmona said.
”What I can say is we are very happy and extremely thankful for the warmth you have given us. We’ve done something historic. Women's football is here to stay.”
Carmona celebrated her goal by lifting her shirt and revealing a tribute to a friend who had recently lost her mother.
The message “Merchi” was hard to read, leaving thousands of people scrambling to social media for answers.
One initial theory was that it was a nod to her former school but Carmona cleared it up on fulltime.
“First of all, I want to say that this victory, this achievement, goes to the mother of one of my best friends who has recently passed away.
“I celebrated the goal with her shirt and from here, I dedicate this to the whole family with all my love.”
Carmona wore the armband during the final with regular captain Ivana Andres named on the bench after struggling with an injury.
She handed it back to Andres for the trophy ceremony.