League spokesman Michael Signora tweeted that the league told its 32 clubs on Friday that players may wear special shoes and gloves from official NFL equipment licensees for Week 1 games.
The move came one day after Chicago linebacker Lance Briggs tweeted that he had expected to be fined for wearing red, white and blue cleats and gloves designed by Reebok. Briggs said it would be "by far the best fine he will ever have to pay."
NFL spokesman Greg Aiello said the league does not "anticipate any issues."
"We have extensive plans for Sunday to respectfully recognize the significance of the day," Aiello said in an email. "Lance Briggs and all players will participate."
Briggs declined to comment when he left the practice field Friday. He instead put the shoes on display in the locker-room, the back of the left shoe bearing the word "Never" and "Forget" on the other shoe.
Coach Lovie Smith said he has no problem with Briggs defying the NFL dress code in this instance.
"I mean, we're going to do an awful lot before the game as an organization -- the NFL as a league -- to honour the victims," Smith said. "But you know, if they (the NFL) say it's OK and the guys are good with it, of course we're all for it, too."
Kansas City Chiefs running back Jamaal Charles also said on his Twitter account that he plans to wear Reebok-issued gloves and cleats to honour the day.
Like Briggs, Charles posted a picture online. It showed an all-red bottom surface around the cleats beneath a white shoe with large blue stripes wrapped around it and white stars along the heel. The back of the glove is all red, with the words, "Never forget," circled around the date, Sept. 11, 2001. The palm of the glove is blue, with white stars.
"I never forget," Charles tweeted.