The 22-year-old, who was strongly touted as a Manchester United target, signed for the Champions League winners on Sunday in a deal that could earn Barca £21.6m.
Guardiola had previously worked with the Spanish midfielder during his hugely-successful spell in charge of the Catalan giants, and Thiago has admitted that his former manager's presence at Bayern helped persuade him to swap La Liga for the Bundesliga.
He told Bayern's official website: "On the one hand, there's the history of the club, which has been one of the best in the world for many years. On top of that, this team plays very attractive football. And I believe the arrival of Pep Guardiola will provide an additional boost.
"We've known each other for a long time and he's a coach who has placed great faith in me. I'm a huge fan of the way he likes football to be played.
"There aren't many coaches in the world with his ability. He was definitely one of the important reasons for me making the move to Munich."
Thiago scored twice in 31 Barcelona appearances last season.