Jerome Boateng trains with Bayern Munich ahead of potential return
The club wrote on its website that Boateng was "among those involved" in Sunday's session, adding the defender "will continue to train over the coming days".
Free since the expiry of his contract with Lyon in June, Boateng, 35, could serve as a backup solution for Bayern coach Thomas Tuchel.
Bayern currently have only three recognised central defenders - Dayot Upamecano, Kim Min-Jae and Matthijs de Ligt - with the latter having missed his side's 2-2 draw with RB Leipzig on Saturday due to injury.
Tuchel was also forced to play midfielder Leon Goretzka and wing-back Noussair Mazraoui in central defence in Bayern's Cup tie against Muenster on Tuesday, which the German champions won 4-0.
Boateng played for Bayern from 2011 to 2021, winning the 2013 and 2020 Champions League titles, as well as the 2014 World Cup with Germany.
Boateng is also currently undergoing a continuing court procedure in Bavaria for domestic violence.
A German court last month threw out the assault conviction against Boateng for attacking his ex-girlfriend in 2018 and ordered a new trial.