The move will combine the nation's second-largest wireless carrier with its biggest satellite television provider. The Justice Department already cleared the deal, which will create a company with about 26 million cable and satellite subscribers.
The purchase previously came under scrutiny for possibly reducing competition, but the FCC determined it is "in the public interest." Under conditions of the agreement, AT&T-DirecTV will be required to expand high-speed fiber optic broadband access to 12.5 million customer locations and offer discounts to low-income consumers.
"The conditions imposed by the commission address potential harms presented by the combination of AT&T, one of the nation's largest telephone and Internet service providers, and DirecTV, the nation's largest satellite video provider," the agency said in a statement.
Additionally, the FCC will prohibit the company from applying discriminatory terms or conditions based on how much data a customer uses. Internal and external compliance officers will also monitor how the company keeps with the terms of the deal.
The deal was first announced in May 2014. It was not clear when the purchase would close.
—The Associated Press contributed to this report