The injury occurred on Tuesday in Palm City, Florida.
The driver, whose name is being withheld in the interest of privacy, reportedly visited a house where an Eastern Diamondback rattlesnake was coiled up near the front door.
The driver likely didn't spot the snake, as she was bit on the back of the leg while placing the package outside the door.
Eastern Diamondbacks are highly venomous snakes. The driver began to feel the effects of its venom right away and called 911 for assistance, according to CBS News.
"Our thoughts are with the driver and we hope for a full recovery after this frightening incident. Together, with the Delivery Service Partner, we're looking into the circumstances surrounding this incident and continue to make sure that drivers understand they should not complete a delivery if they feel unsafe," Amazon spokesman Branden Baribeau said in a statement.
The Eastern Diamondback is fairly common in the region where the worker was bit, according to the Martin County Sheriff's Office. One snake packs enough venom to kill five humans, though typically snakes are not aggressive and only strike when humans wander – often unintentionally – too close to them.
Florida's Poison Control Centre advises anyone bitten by a rattlesnake to immediately seek medical care.
This isn't the first time this year a delivery driver has had a close encounter with a rattlesnake on a porch; a FedEx driver in Nebraska narrowly avoided a bite while he was making his rounds in August.
He dropped off the packages he intended to deliver, but was startled by the sharp rattle let off by the agitated snake.
The FedEx driver ultimately killed the snake using a shovel and a rake.
"I hope you didn't have a pet rattlesnake at your front door because I killed him. Sorry about the blood," the driver said in a text to the homeowner.
The woman who owned the house was grateful and asked the delivery company to make the man their employee of the year.
In both instances, the rattlesnakes were likely seeking shade during the hot summer afternoons to help regulate their body temperature.