McCarthy said a show of owners' hands was asked to check support, a process which is often used. There were zero nays.
Raiders owner Mark Davis and 49ers owner Jed York abstained from the vote.
The new policy says that players do not need to be on the field for the national anthem, giving them the option to stay in the locker room.
Teams will be fined if any personnel "do not show proper respect for the flag and Anthem” on the sidelines.
The protests during the national anthem started in August 2016 when former 49ers quarterback Colin Kaepernick refused to stand for the 'Star-Spangled Banner' as a means of protesting racial inequality and police brutality. Dozens other NFL players, as well as numerous other athletes across America, ultimately joined him. The protests grew during the 2017 season after Trump criticized NFL players who chose to follow suit. Trump said owners should "fire" NFL players who protest the anthem and referred to them as "son[s] of b------". Players responded by protesting en masse.