He was signed on a free transfer on the final day of the transfer window with the 32-year-old striker putting pen to paper late on Monday evening.
The former Arsenal skipper has not played for the Gunners since a disciplinary breach in December but scored 92 goals in 163 games prior to that, a BBC report noted.
Auba as he is known had reportedly turned down a chance to join Saudi-side Al-Nassr flying to Spain rather to complete the move to Barcelona, even though some reports suggested that the club was unsure if it will fall through.
He was brought in in the final season of coach Arsene Wenger from German side Borussia Dortmund for £56m with about £15m in wages.
Arsenal manager Arteta stripped him off the captaincy because of disciplinary issues. He was the club’ highest-earning player at the time of leaving.
Arsenal now have only two strikers for the remainder of the season. Auba’s successor as captain, Alexandre Lacazette and Eddie Nketiah.
Aubameyang was sent home early from the Africa Cup of Nations in January because of ongoing health issues.
The forward missed Gabon’s draw with Ghana after scans revealed “heart lesions” following a bout of Covid, although later scans gave him the all-clear.
The story of the deal
Spanish football writer Guillem Balague for the BBC:
Aubameyang got a private jet to take him to Barcelona and the Spanish club had booked a medical for him because it looked like the move was going to happen.
It wasn’t related to Ousmane Dembele’s departure from the Nou Camp, but if the French forward had gone, Barca would have been able to pay larger wages.
Then, at 6 pm, it looked like the move was not going to happen and the financial differences between the two clubs were too big.
This whole affair has been relayed to us almost minute-by-minute by Barca president Joan Laporta, who is at a Mundo Deportivo awards event. Laporta is in the business of giving hope to the fans and has been describing the situation as it unfolds.
It looked like the transfer wasn’t going to happen because the difference in what Barca could afford in wages and the percentage of Aubameyang’s wages, that Arsenal were prepared to pay, was too great.
Barcelona had 2m euros (£1.6m) in wages to pay and Aubameyang was happy to accept any payment In the end. Then Arsenal accepted a free transfer. That means the Gabon forward may just get 2m euros this season – rather than the circa 9m euros (£7.5m) he was due at Arsenal – and more later.