Olga Carmona, whose goal won the Women's World Cup for Spain at Stadium Australia, learned of her father's death after the final.
The Spanish soccer federation announced the news late on Sunday in Madrid but did not say when Carmona's father died or give a cause of death.
"And without knowing it, I had my Star before the game started," Carmona wrote on social-media platform X, formerly known as Twitter.
"I know that you gave me the strength to achieve something unique. I know that you were watching me tonight and that you are proud of me. Rest in peace, dad."
After the final whistle of Spain's 1-0 win over England in the tournament's showpiece game, the 23-year-old Carmona celebrated and danced on the field, and appeared to participate normally during the trophy presentation.
"We love you, Olga," the federation said on social media.
"You are part of the history of Spanish soccer."
Carmona scored with a left-footed strike in the 29th minute to give Spain victory over England as the month-long World Cup in Australia and New Zealand reached its climax in Sydney.
She had also scored a late winner in La Roja's 2-1 last-four win over Sweden, making her the first player since American Carli Lloyd in 2015 to score in a Women's World Cup semi-final and final.
As well as helping her country lift the trophy for the first time, Carmona was also named the final's most valuable player on Sunday.
She celebrated her goal with a tribute to a friend who recently lost her mother.
"All of us, we felt that this team had something special," the Real Madrid defender said after Spain won the title.
Madrid released a statement on Sunday night about her father's death and offering condolences to the player and her family.
Carmona's Spain teammate Irene Paredes lost her father a few days before the team began their preparations for the World Cup. The defender dedicated the title to him on Sunday.
Before the news of the death of Carmona's father was made public, the federation said title celebrations were set to take place after the squad's arrival in Madrid on Monday night.
Australian Associated Press