Stanway, 27 years and 88 days, surpassed Keira Walsh's record of 27 years and 184 days. The midfielder partnered Momoko Tanikawa in Bayern's defensive midfield as they hosted the second leg at Allianz Arena.
Bernadette Kakounan replaced Arianna Caruso in Bayern's starting lineup for the 5:45pm BST kick-off, with the German side aiming to secure their place in the next round of the competition.