He said: “Very, very excited, though it was kind of hard to wait.
“I knew it would happen. I have been very calm at the hotel with my family and agents. It’s stuff I don’t understand. All my part was done, I was ready. It was stuff above me – legal things and very small details.”
Gordon spoke in Spanish during his presentation and said he learned the language because he “believed he would play for Barca as a kid”.
He spent three and-a-half years with the Magpies after joining from Everton in January 2023, making 152 appearances, and was their top scorer this season with 17 goals in all competitions.
Gordon will fly out with the England squad to the United States on Monday for a training camp before the World Cup, which starts on 11 June.
He will join compatriot Marcus Rashford at Barca, but the Spanish club are yet to trigger an option to make the 28-year-old forward’s loan move from Manchester United permanent for £26m.