Barca confirmed a deal with Las Palmas to sign the highly rated 17-year-old in September 2019, but he stayed at the second-tier club for the remainder of the campaign.
He was finally unveiled as a Barcelona player on Thursday, however, with president Josep Maria Bartomeu and new sporting director Ramon Planes – who has replaced Eric Abidal in the role – present at the ceremony.
Pedri – who revealed he idolizes Andres Iniesta – is excited at the prospect of working alongside Messi, provided the forward remains at Camp Nou amid continued speculation over his future.
"It's not every day you can sign for this club," Pedri said.
"I'm really looking forward to doing great things, but the pressure is the worst a footballer can have. You have to get rid of it as soon as possible and replace it with excitement.
He added: "My idol has always been Andres Iniesta and now I want to learn from the best, which is Leo Messi."
As for his own situation, Pedri is planning for life at Barca but is also prepared for a temporary move away, a spell out on loan potentially offering him the chance to play regularly and aid his long-term development.
"The first option is to stay here and have fun with the best, although a transfer is not an option that I've ruled out," he admitted.
"You have to take [pressure] off from the first moment. You must have enthusiasm to enjoy each day and hope that everything goes well."
It has been a busy week for Bartomeu and Barca, who parted ways with Quique Setien after the humbling Champions League exit to Bayern Munich that has increased concerns Messi may leave.
Ronald Koeman has since been appointed as head coach, while presidential elections have also been moved forward to March 2021.
"With Pedri we bring in one of the most talented players of his generation and a Barca fan since he was a child," Bartomeu tweeted, along with a picture of him stood alongside the club's new recruit.
"He brings the excitement and ambition we need for this new project and to be a success at Barca."