Pjanic is joining Barca for a fee of €60m in bonuses as Arthur Melo moves in the opposite direction for €72m plus €10m.
Bartomeu said of the Bosnian: “We have been following him for a long time. But it couldn't be done in recent years because the club didn't want to sell him.
"He has always been delighted with the idea of coming to Barça. It wasn't a surprise transfer.
"He will easily establish himself as an important player."