The Brit singer, 25, was snapped in the back of a car following the iTunes Festival 2013 gig and almost went unnoticed due to her lack of trademark thick eyeliner.
Adele, who gave birth to a baby boy last October, had swept her honey blonde hair back into an updo and simply added a touch of blusher, mascara and lippy.
She was also wearing a brown and cream patterned blouse and topped off her outfit with a pair of gold hoop earrings.
The concert was held at Camden's Roundhouse in London and Lady Gaga was also pictured leaving - in a dress that actually blew bubbles!
Gaga had showcased mainly new material at the gig and One Direction star Niall Horan was also in the audience.
The iTunes Festival will run for the remainder of September, and the artist line-up includes Katy Perry, Justin Timberlake, Ellie Goulding and Robin Thicke.
Would you have recognised Adele? Tell us below, as the best comment from across the website each week wins £50!