This is the first coronavirus vaccine approved by the FDA and is expected to open the door to more vaccine mandates.
In a statement, the FDA said its review for approval included data from approximately 44,000 people.
The vaccine, which will now be marketed as Comirnaty, was found to be 91% effective in preventing the COVID-19 disease.
The Pfizer/BioNTech vaccine has been authorised for emergency use in the United States since mid-December for people 16 and older.
In May, the authorisation was extended to those 12 and older.
Out of more than 170 million people in the United States fully vaccinated against COVID-19, more than 92 million have received the Pfizer/BioNTech vaccine.