Barcelona confirmed the deal on Tuesday after the Brazilian passed a medical the previous day, with his contract running to 30 June 2028 and carrying the option of a further season.
The transfer had been reported as close throughout Monday, with Arsenal accepting a fee in the region of £8.6m (€10m) — well short of what Barcelona had hoped to spend on a new centre-forward before turning to a cheaper alternative once their top target proved unattainable.
That target was Julián Álvarez. Barcelona's move for Jesus only gathered pace once Atlético Madrid made clear they had no intention of selling the Argentina international to a direct rival, leaving sporting director Deco to identify a more affordable route to reinforcing Hansi Flick's attack.
Napoli had also registered interest in Jesus during the window, but the player opted for a return to LaLiga instead.
Speaking to reporters after landing in Barcelona, Jesus kept his early comments brief but pointed.
"I'm very happy. Hopefully we win lots of titles," he said, before addressing the fitness concerns that have shadowed the move. Asked directly about the anterior cruciate ligament injury that disrupted his final season in England, he was unequivocal: "My knee is perfect."
Jesus fell down the pecking order at Arsenal in recent seasons, hampered by injury problems and by the emergence of Kai Havertz and Viktor Gyökeres as Mikel Arteta's preferred options through the middle.
He joined the Gunners from Manchester City in 2022, going on to score 32 goals and add 22 assists in 123 appearances, having previously scored 95 goals in 234 games during his time at the Etihad — output that leaves him with 127 goals in total across both spells in the Premier League.
Flick had wanted a more traditional focal point up front than Jesus, who is more comfortable dropping into deeper areas and combining than acting as a fixed number nine, but he is expected to provide competition and cover in an attack that has relied heavily on Raphinha as its central reference point since the departures of Robert Lewandowski and Ferran Torres.
Jesus is due to be presented officially at Camp Nou this week, having already watched Monday's 5-2 win over Rayo Vallecano from the stands as a guest of the club, an early glimpse of the side he will now be tasked with helping to lead the line for.