The 32-year-old former Gunners captain was visible in pictures from Barcelona training posted on social media on Tuesday.
The Gabonese striker arrived in Spain on Monday just ahead of the end of the January transfer window. But the clubs did not announce a deal before the deadline passed. His release by Arsenal makes him a free agent, able to sign outside the window.
“Pierre-Emerick Aubameyang has left the club by mutual agreement,” the Premier League club said in a statement.
“We wish Aba all the best for the next chapter in his career and thank him for his contribution to the club.”
He has not played for Arsenal since being disciplined by the club in December. He was reportedly one of the top-paid players in the Premier League with a basic salary of around 250,000 pounds (300,000 euros or 330,000 dollars) a week.
Aubameyang joined Arsenal from Borussia Dortmund on the last day of the 2018 January transfer window for a reported 56 million pounds, a club record at the time. In almost exactly four years at the club, he appeared in 165 competitive games and scored 92 goals.
In January, Aubameyang was part of the Gabon squad at the Africa Cup of Nations in Cameroon but missed the first two games with coronavirus before being sent homme after team medical staff said they had detected “cardiac lesions”.
The British Press Association reported that Arsenal delayed announcing Aubameyang’s departure as a gesture of respect to Barcelona, whose president, Joan Laporta, said on Tuesday that the official unveiling may come later in the week.