In April, T-Mobile and Sprint announced the proposed $26 billion deal, which unsurprisingly garnered a lot of questions around anticompetitiveness.
The companies argued that the two stood a better chance to compete against AT&T and Verizon as a single entity.
The deal was approved by the Justice Department in July.
Now with the FCC's blessing, the only hurdle is a multi-state lawsuit that both companies have vowed to resolve before the deal closes.
The report states that Democrats Rosenworcel and Starks dissented in today's vote, while Republican commissioners Ajit Pai, Brendan Carr and Michael O'Rielly voting in favor.
"We've all seen what happens when markets become more concentrated after a merger like this one. In the airline industry, it brought us baggage fees and smaller seats. In the pharmaceutical industry, it led to a handful of drug companies raising the prices of lifesaving medications," Commissioner Jessica Rosenworcel said in a statement, noting she did not vote for the merger.
"There's no reason to think this time will be different. Overwhelming evidence demonstrates that the T-Mobile-Sprint merger will reduce competition, raise prices, lower quality, and slow innovation."