WASHINGTON — The Federal Communications Commission voted Thursday to regulate broadband Internet service as a public utility, a milestone in regulating high-speed Internet service into U.S. homes.

Tom Wheeler, the commission chairman, said the FCC was using “all the tools in our toolbox to protect innovators and consumers” and preserve the Internet’s role as a “core of free expression and democratic principles.”

The new rules, approved 3-2 along party lines, are intended to ensure that no content is blocked and that the Internet is not divided into pay-to-play fast lanes for Internet and media companies that can afford it and slow lanes for everyone else. Those prohibitions are hallmarks of the net neutrality concept.

Explaining the reason for the regulation, Wheeler, a Democrat, said that Internet access was “too important to let broadband providers be the ones making the rules.”

Mobile data service for smartphones and tablets, in addition to wired lines, is being placed under the new rules. The order also includes provisions to protect consumer privacy and to ensure that Internet service is available to people with disabilities and in remote areas.

Before the vote, each of the five commissioners spoke, and the Republicans delivered a scathing critique of the order as overly broad, vague and unnecessary. Ajit Pai, a Republican commissioner, said the rules were government meddling in a vibrant, competitive market and were likely to deter investment, undermine innovation and ultimately harm consumers.

“The Internet is not broken,” Pai said. “There is no problem to solve.”

The impact of the new rules will hinge partly on details that are not known. The rules will not be published for at least a couple of days and will not take effect for probably at least a couple of months. Lawsuits to challenge the commission’s order are widely expected.

The FCC is taking this regulatory step by reclassifying high-speed Internet service as a telecommunications service, instead of an information service, under Title II of the Telecommunications Act. The Title II classification comes from the phone company era, treating service as a public utility.

But the new rules are an a la carte version of Title II, adopting some provisions and shunning others. The FCC will not get involved in pricing decisions or the engineering decisions companies make in managing their networks. Wheeler, who gave a forceful defense of the rules just ahead of the vote, said the tailored approach was anything but old-style utility regulation. “These are a 21st-century set of rules for a 21st-century industry,” he said.

Opponents of the new rules, led by cable television and telecommunications companies, say adopting the Title II approach opens the door to bureaucratic interference with business decisions that, if let stand, would reduce incentives to invest and thus raise prices and hurt consumers.