Investigators say the man was parked next to the woman at the 76 Station on Yosemite Avenue.
When the woman went inside the station to pay, the man grabbed her purse filled with a large amount of cash and credit cards, then drove away.
Surveillance footage from the gas station shows the man was dressed in dark clothing. Investigators are asking the public to help identify him and the vehicle he drove.
Anyone with information is asked to contact the Madera Police Department at 675-4220.