Many Internet service providers had opposed the definition change. The ruling enhances the FCC's legal power to push providers to boost connection speeds to levels it deems suitable.
Read MoreNet neutrality decision expected from FCC in February
The FCC could also use the scope of the law to allow easier entry into broadband markets, including by municipalities. The change comes amid a pending $45 billion merger of Comcast and Time Warner Cable, giants who the rule would affect.
Comcast holdings include NBCUniversal, the parent company of CNBC.
The FCC could also use the standard to guide its decisions on doling out subsidies that encourage broadband deployment and network improvements. The agency has not typically used reports like the one that set the broadband definition to tighten regulations, experts told Reuters.
This year has already proven busy for the government agency, which on Tuesday warned hotels and other entities not to block access to personal Wi-Fi hotspots. It also continues to consider proposals on net neutrality law.
Read MoreUS FCC warns against blocking personal Wi-Fi access
—Reuters contributed to this report.