Pjanic, a Bosnia and Herzegovina midfielder, will join Barca for €60m plus €5m in possible add-ons and has agreed a four-year deal with a €400m release clause. Juve will pay Barca €72m for Arthur with a further €10m in potential add-ons.
Both players will remain with their sides for the duration of their respective domestic campaigns, while they will also be available for the Champions League in August, throwing up a scenario where they could have to play against their future clubs in Lisbon.
Arthur, 23, has agreed to a five-year deal with Juve, with sources telling ESPN he will earn significantly more than he is currently earning at Barca. The Brazil international was in Turin on Sunday where he underwent a medical and signed his contract.
He returned to Barcelona for training on Monday, telling his teammates ahead of Tuesday's game against Atletico Madrid at Camp Nou that he would continue to give his all until he leaves for Juve at the end of the season.
Throughout negotiations, Arthur, a €30m signing from Gremio in 2018, had always expressed his desire to stay at Barca. However, the pressure exerted by the club, in addition to Juve's generous offer, finally forced him to change his mind.
Compared to Xavi in his first few months at Barca, sources at the club told ESPN there is a feeling Arthur stagnated over the past year, though the primary reason for the sale is financial.
As reported by ESPN in May, Barca needed to bring in around €70m in player sales before June 30. There were a number of reasons for that, including the fact the budget had presumed €124m in sales for the 2019-20 season.
Meanwhile, due to the losses accumulated because of the coronavirus pandemic, the board of directors faced the possibility of recording huge losses for the financial year.
That could have subjected them to action from the club's members, while they could even find themselves in a position where they have to personally guarantee any losses moving forward due to the complicated legislation surrounding the ownership model for member-owned clubs in Spain.
However, they will hope the money banked from the sale of Arthur will spare them from that, while the Pjanic fee will be amortised over the course of his contract.
It's not the first time they have come up with an imaginative way to balance their accounts. They used the same method last June when they swapped Jasper Cillessen for Valencia goalkeeper Neto in separate deals worth around €30m each.
Barca have tried to sign Pjanic several times in recent seasons but negotiations intensified with Juve, who also needed to balance their accounts, in the past two months.
The two clubs and Pjanic, who sources told ESPN is excited to be joining Barca, quickly came to an agreement, but Arthur remained adamant he wanted to stay put in Spain.
He released a statement in April explaining he was going nowhere and then, as reported by ESPN, in May he told both Barca and Juve that he had no intention of being involved in any deal.
However, with both clubs still pursuing the deal, and seeing how Barca were pushing for him to leave, Arthur finally performed a U-turn on his decision and gave the green light to the transfer.
Arthur, who is seven years Pjanic's junior, was also won around in the end by Maurizio Sarri's desire to take him to Turin. The Juve coach envisages him as the centrepiece of his midfield moving forward.