Monday's vote comes a week after the council repealed rules it passed four months ago, which would have limited the number of rideshare cars from each service to 150 on the road at any given time.
Seattle Mayor Ed Murray last month brokered a deal that eventually led to the repeal of the old ordinance and to Monday's legislation.
The mayor had said the compromise - reached between taxi drivers, rideshare companies and others - encourages innovative transportation choices in the city while also recognizing the taxi industry's historic role.
Politicians in Seattle and other places have been attempting to regulate fast-evolving "transportation network" companies such as Uber, Lyft and Sidecar.
People can get a ride by using an application on a smartphone or tablet, a system many users say is more reliable than hailing a cab or calling taxi company operators. They pay for the ride through the app.
Rideshare companies had said the cap passed in March would hurt their businesses, and they gave heavily to a campaign to repeal those rules through a referendum. Meanwhile, taxi drivers had said the companies had an unfair advantage because they weren't licensed or regulated.
The new rules passed on Monday adds 200 new taxi licenses in the city during the next four years, details insurance and licensing requirements for rideshare companies, and allows hailing rights for for-hire vehicles, among other provisions.