The Federal Communications Commission's 3-2 vote in favor of so-called "net neutrality" followed an intense debate in Washington pitting backers of online services like Netflix, Twitter and Yelp against big Internet service providers like AT&T and Verizon.
The ruling, climaxing a years-long regulatory battle, sets a new standard that treats all Internet traffic as equal, preventing Internet firms from charging fees for better access.
Backers said the move guarantees Internet users can roam freely online and prevent any effort to stifle expression, but critics complained it would give the government too much control.
FCC chairman Tom Wheeler said the plan would foster a free and open Internet where broadband services cannot be "gatekeepers" for what is available online.
"The Internet is the ultimate tool for free expression," Wheeler said ahead of the vote.
"The Internet is too important to allow broadband providers to be making the rules."
Commissioner Mignon Clyburn said the measure would "give those with deep pockets as well as empty pockets the same opportunity to succeed."
Also voting for the plan was Commissioner Jessica Rosenworcel, who said, "We cannot have a two-tiered Internet that speeds the traffic of the privileged and leaves the rest of us lagging behind."
Internet as public utility
The plan unveiled earlier this month by Wheeler regulates broadband Internet service providers as "public utility" carriers, revamping the agency's rules struck down by a federal court last year.
In response to a court decision which said it lacked authority, the FCC reclassified Internet service providers as "common carriers" under a 1934 telecom law, while promising to steer clear of rate regulation and other provisions of that law.
The new rule also applies the concept to mobile Internet carriers, preventing them from blocking or throttling content for competitive reasons.
President Barack Obama, who urged the FCC in November to adopt rules enshrining the concept of "net neutrality," welcomed the FCC action, saying it will "protect innovation and create a level playing field for the next generation of entrepreneurs."
The plan prohibits service providers from blocking lawful content or slowing one service, such as streaming video operator Netflix, to support a rival like Hulu.
But the years-long battle may not end with the FCC vote. The ruling is likely to face fresh court challenges, and the Republican-controlled Congress could seek to overturn or modify the regulations.
Critics say the plan amounts to old-style regulation based on a Depression-era law regulating telephone companies, and that the FCC will be hard-pressed to selectively enforce provisions of the law.
Commissioner Ajit Pai, one of the two dissenters, said the plan "marks a monumental shift toward government control of the Internet."
The second dissenting commissioner, Michael O'Rielly, called the effort a "power grab" and said it amounted to "back door rate-setting authority."
O'Rielly said that the regulations would chill investment while adding new fees to broadband, making it more difficult to get faster Internet to all.
Cable giant Verizon which filed the challenge resulting in last year's court ruling said the plan would "encumber Internet services with badly antiquated regulations" and would lead to "uncertainty for consumers, innovators and investors."
But Harold Feld at the consumer activist group Public Knowledge, called the vote a win for Internet users.
"It means the Internet is not going to be like your cable service, where the provider decides what package you get and what you can see," Feld told AFP.
Ed Black of the Computer & Communications Industry Association, which represents many tech firms, called the decision "historic."
"The action the FCC has taken will be remembered for decades to come as the action that ensured the next generation of innovators will have that same access to customers and the Internet so that they too can succeed and grow our economy," Black said.
In a separate decision, the FCC, also in a 3-2 vote, said it would use its authority to overturn state rules in North Carolina and Tennessee that block municipal broadband firms from expanding, saying the decision will help promote expanded access to high-speed Internet.