The most commented play on Facebook was Neymar's first goal, which levelled the match after Brazil fell behind early with an embarrassing own goal. The second most talked-about play was the controversial penalty that led to Neymar's second goal, putting Brazil ahead for the first time.
With 16 million posts, Brazil was the most active country on Facebook during the game, followed by the United States and England.
"That number represents more than 20 times the capacity of all the stadiums of the World Cup," Facebook said in a statement.
The World Cup is a big business opportunity for companies like Facebook as fans around the world turn to social media to comment on live events.
The most active demographic group during the opening match was men between 18 and 24 years old, Facebook said.
© Thomson Reuters 2014