The agency acted a day after an advisory committee recommended approval of the vaccine.
Shares of Moderna added 2.24% in late trade Friday, after falling 2.6% in the regular session.
The Cambridge, Mass.-based drugmaker's mRNA 1273 vaccine, was given the thumbs-up by the Vaccines and Related Biological Products Advisory Committee with a 20-0 vote Thursday night.
Moderna's vaccine is the second approved for use in the U.S. Last week a vaccine jointly developed by Pfizer (PFE) - Get Pfizer Inc. Report and BioNtech (BNTX) - Get BioNTech SE Report was cleared for use by the FDA. The first round of inoculations using that vaccine was administered this week.
The vaccines are arriving as Covid cases have surged to record levels throughout the U.S. killing thousands and overwhelming hospital ICUs.
Johns Hopkins University reported 233,000 new coronavirus infections in the United States Thursday, a 3% increase from last week's levels that takes the overall total past 17.3 million. More than 300,000 people have died of the disease in the U.S. since the outbreak of the pandemic.
In Europe, Christmas lockdowns have been put in place in France, Italy and Germany with a multi-tiered system of travel and gathering restrictions in the United Kingdom
Modena has said it could have 20 million doses available for the U.S. market this year, and a total supply of between 500 million and 1 billion doses worldwide next year.
U.S. Army General Gustave Perna, who is coordinating the government's Operation Warp Speed vaccine rollout, said some 5.9 million doses of the Moderna vaccine could be rolled out next week.
Contracts with the U.S. government, as part of Operation Warp Speed, as well as those signed with Britain and the European Union, provided an early revenue boost for Moderna, while extended orders through 2021 and beyond could increase its topline to around $4.5 billion, analysts have estimated.