Chile midfielder Vidal has agreed to join Barca on a three-year deal , with just a medical remaining to conclude a transfer understood to be worth in the region of €20 million (£18m/$23m).
The 31-year-old is Barca's fourth major recruit of the close season following Brazilian midfielder Arthur's arrival from Gremio, the capture of Bordeaux winger Malcom at Roma's expense and defender Clement Lenglet's switch from LaLiga counterparts Sevilla.
"Thanks to FC Bayern and all fans," Vidal said in a brief statement on the Bundesliga champions' official website.
"I really enjoyed the time in Munich. I would like to thank the club for giving me another chance to take on a new challenge in Barcelona. "
He scored 22 goals and supplied 18 assists over the course of 124 competitive games, winning three Bundesliga titles in as many seasons.
"I would like to thank Arturo for three great years on behalf of FC Bayern," said chief executive Karl-Heinz Rummenigge.
"We celebrated great success during this time, and Arturo had a significant share in that.
"He has always been at the forefront of important games, we have always been able to rely on him."