Coutinho was left out of the squad for Barca's La Liga opener against Athletic Bilbao on Friday, with club director Guillermo Amor confirming the Brazilian is close to joining Bayern.
“We can confirm that there is an agreement in principle for the loan of Coutinho to Bayern and we just have to finalise the deal,” Amor told Movistar, ahead of the game at San Mames.
Bayern sporting director Hasan Salihamidzic also confirmed the loan deal later on Friday.
“I can confirm that we were in Barcelona and have agreed terms with the player and his agent,” Salihamidzic told broadcaster ZDF following Bayern's own league opener, a 2-2 draw with Hertha Berlin.
“We have a good relationship with Barcelona. We are still missing a few details such as the signature and the medical, but we are happy to have got a player like him.”
Coutinho joined Barcelona from Liverpool in January 2018 for an initial 120 million euros ($133 million), plus another 40 million euros in potential add-ons.
But despite huge excitement around Coutinho's arrival, he has struggled to find his place at Camp Nou.
Initially tried in midfield, Coutinho was pushed into the front three by Ernesto Valverde last season in a bid to help him rediscover his best form.
Yet the 27-year-old was too often a bystander in games and some suggested his style and positioning clashed with Lionel Messi.
Gerard Pique was asked earlier this month about the possibility of Coutinho leaving. “I want him (Coutinho) to stay,” Pique said. “But at the end of the day it's what he wants and I want him to be happy.”
At Bayern, the Brazilian will provide welcome reinforcement in attack following the departure of Arjen Robben and Franck Ribery at the end of last season.
Coutinho's departure to Bayern could also have implications for Barcelona's hopes of re-signing Neymar from Paris Saint-Germain.
Barca have already spent around 250 million euros this summer and it had been suggested PSG were keen for Coutinho to be included in any bid.
“There is a lot of talk about Neymar at the moment,” Amor added. “He is in the newspapers every day and I don't think we should get into it now.
“Anything can happen while the market is still open but for now there is nothing and Neymar is a PSG player.”