On the recording, a man's voice repeatedly says, "Hello, please don't do that again." He calls Kealey an "idiot", saying "you bring me here and you cancel", before adding "Do that again and I'll cut your neck."
Kealey told BuzzFeed News the message was sent to her on Sunday.
She said she'd booked the car at 11 am as she was meeting friends for brunch, but cancelled it while it was "a few minutes away".
"The irony is I cancelled the cab because I occasionally get panic attacks," she said, "and right after I called it I began to feel anxious so I decided to walk instead to calm myself down and tell my friends that I would be late."
Kealey hadn't checked her voicemails until today during her lunchbreak. "It completely shocked me. The language is so inappropriate, threatening, and disgusting. It's extra scary since I ordered it right by my house. It makes me feel so unsafe."
Uber responded to Kealey's complaint on Twitter.
She told BuzzFeed News that Uber had told her they would work with the police. She has sent the company the audio clip.
There have recently been complaints from female drivers in America – revealed by BuzzFeed News – who said a feature designed to protect them in fact opened them up to harassment from male passengers weeks later because their numbers had not been deleted from the system.
An Uber spokesperson issued the following statement in response to Kealey's experience: "We have spoken to the rider to ensure they are OK and encouraged them to report this the police. The driver has been immediately suspended, as is our policy, and we are investigating fully."
The spokesperson confirmed that the anonymised number used is "no longer available" and added that "all feedback on the Uber app is also anonymous so the driver would not be aware of this riders complaint".