Google has long stated its intent to skip driver-assist systems and go directly to fully autonomous driving.
Over the next few months, we'll be inviting members of the public to take trips in our fully self-driving vehicles.
In a speech at the Lisbon Web Summit on Tuesday, Waymo CEO John Krafick said, "We recently surveyed 3,000 adults across the USA, asking them when they expected to see self-driving vehicles - ones without a person in the driver's seat - on their roads".
The company also says it has redundant braking, steering, power and computing systems so it never has to rely on a human driver. This one, however, may not have anyone in the driver's seat.
Phoenix has very consistent sunny weather and wide roads.
"This demonstrates Waymo's confidence in the ability of these vehicles to function at least in this environment", Abuelsamid said. It's a major step toward vehicles driving themselves without human backups on public roads.
A self-driving electric shuttle built by Navya was tested early this year in Las Vegas in a USA first and will start a regular route there on Wednesday, the company told AFP.
But this latest move will greatly increase the ambition, and risk, of Waymo's technology - it will eventually cover an area the size of Greater London, the company said.
The testing will initially be limited to part of Phoenix, Arizona. It has a fleet of 100 autonomous vans in Phoenix, with plans to add 500.
For now, you'll also have to be a member of Waymo's Early Rider program to join in on the fun, and you'll also still have to deal with a Waymo employee hanging out in the vehicle with you. Vehicles developed by rival Uber - which is locked in a bitter legal fight with Waymo over the technology - has covered more than a million miles and allowed Pittsburgh residents to hitch rides in autonomous vehicles spinning through the Pennsylvania city's streets.
Waymo, formerly known as the Google Self-Driving Car Project, is getting into the ride-hailing business, but with a twist.
Waymo is not the first company to test its driverless cars on public roads. The trial in that high-profile case is scheduled to begin in early December. No date has been released for the launch of the commercial endeavour, but just setting a vague timetable is a change from last week when Gizmodo took a ride in one of Waymo's self-driving Chrysler Pacifica minivans.