Demonstrations took place in 10 U.S. cities Wednesday, including Chicago, Los Angeles, New York, San Francisco and Washington, as well as some European locations like London.
The protests arrive just ahead of Uber's initial public stock offering Friday. Uber hopes to raise $9 billion and is expected to be valued at up to $91.5 billion.
It's not the first time drivers for ride-hailing apps have staged protests. Strikes were planned in several cities ahead of Lyft's IPO last month, although the disruption to riders appeared to be minimal. More cities are participating in Wednesday's protest.
"Drivers built these billion dollar companies and it is just plain wrong that so many continue to be paid poverty wages while Silicon Valley investors get rich off their labor," said Brendan Sexton, executive director of the Independent Drivers Guild, in a statement. "All drivers deserve fair pay."
In New York, some drivers went offline between 7 a.m. and 9 a.m., though it was still easy to locate a driver Wednesday during rush hour near Wall Street in lower Manhattan.
Drivers in Los Angeles are participating in a 24-hour strike and picket line at Los Angeles International Airport.
Uber, in a prepared statement Wednesday, said it is constantly working to improve the working environment for drivers.
"Drivers are at the heart of our service-- we can't succeed without them-- and thousands of people come into work at Uber every day focused on how to make their experience better, on and off the road."
Lyft said its drivers' hourly earnings have increased over the last two years, that 75 percent of its drivers work less than 10 hours per week to supplement existing jobs and that on average the company's drivers earn over $20 an hour before subtracting expenses such as gas and vehicle maintenance.
"We know that access to flexible, extra income makes a big difference for millions of people, and we're constantly working to improve how we can best serve our driver community," Lyft said.
In New York, striking drivers organized a caravan across the Brooklyn Bridge and are holding rallies outside Uber and Lyft offices in Queens.
Labor actions also took place in Atlanta, Boston, Philadelphia, San Diego and Stamford, Connecticut. -- The Associated Press