The tall 23-year-old Brazilian, once regarded as a huge defensive talent before a string of injuries and a 2012 jail sentence of three years and nine months for burning down his rented Munich villa, cut his Bundesliga career short.
"This time spent in prison, these 13 months, have been hard," Breno, who said had stayed relatively fit in prison, told a news conference, sitting next to club president Uli Hoeness.
"I have changed as a person and I have learned a lot in there. I am happy to be given this chance by Bayern."
Breno will work five-hour-a-day as an assistant coach to the under-23 team and return to prison each afternoon.
"Breno is a member of the big Bayern family, who once had problems," said Hoeness, who himself is facing charges of tax evasion and could stand trial.
"Now there is a glimmer of hope and we want to give it to him," said Hoeness.
Breno, who will most likely have to leave Germany after serving his sentence, is hoping for an early release in 2014.
He had joined the Bavarians from Sao Paolo as a teenager in 2008 but failed to grab a starting spot.
A brief loan spell at Nuremberg in 2010 was cut short by a serious ligament injury before returning to Bayern.
The former Brazil under-23 player was arrested in 2011 after his rented luxury home went up in flames with him at home recovering from injury. He was later convicted of arson.
His family was not at home at the time and there were no injuries.
- Crime & Justice
- Society & Culture
- Uli Hoeness