Gordon has caught the eye since joining Newcastle from Everton in 2023 and recently enjoyed a productive European campaign, registering 10 goals and two assists in the UEFA Champions League.
His Premier League form didn't hit the same heights, with the 25-year-old netting six times in 2025/26, but his overall St James' Park tenure was successful, with 39 goals and 28 assists in 152 appearances.
He played a key role in a period of growth for the Saudi-backed Magpies, who twice qualified for the Champions League and won the EFL Cup - the club's first trophy in over 50 years.
"As soon as I knew (signing for Barça) was a serious possibility, there was never any question," Gordon said. "I always wanted to play for the biggest club on the planet. It’s something I dreamed about as a child. This is a dream come true.
"I know this club comes with a lot of responsibility because of the history and the players who came before me, but I’m ready for that challenge."
Gordon answered some questions in Spanish at his unveiling. "I started learning Spanish because, as a kid, I believed I would one day play for Barcelona," he said. "I even told my physio at Newcastle that one day I’d play here, so I wanted to learn the language."
The England international is due to compete at this summer's World Cup and will be pleased to have any speculation over his future put to bed before the tournament starts.
Three Lions teammate Marcus Rashford spent last season on loan at Barcelona, but there now appears to be some doubt over his temporary move becoming a permanent one.