Spanish journalist Rubio, who is eight years Ramos's senior, agreed to become the 32-year-old player's wife.
"She said yes. I love you… forever," Ramos wrote on his Twitter account, attaching photos of Rubio and himself wearing rings.
Ramos has been dating Rubio since 2012. The couple have three sons, with their youngest son Alejandro born in March.
Ramos scored a spot-kick during the penalty shootout in the round of 16 at the World Cup as 2010 champions Spain bowed out to Russia.