"On this taking the knee thing, I don't know, maybe it's got a broader history, it seems to be taken from the Game of Thrones," Mr Raab told TalkRadio after being asked about Premier League footballers taking the knee last night.
He added: "It feels to me like a symbol of subjugation and subordination rather than one of liberation and emancipation, but I understand people feel differently about it so it's a matter of personal choice."
He said he would only perform the action "for two people: The Queen and the missus when I asked her to marry me".
Mr Raab’s comments drew fierce criticism from Labour, with shadow justice secretary David Lammy describing the remarks as “deeply embarrassing”.
The foreign secretary later took to Twitter to say he has "full respect" for the Black Lives Matter movement.
He added: "If people wish to take a knee, that’s their choice and I respect it. We all need to come together to tackle any discrimination and social injustice."
Mr Lammy tweeted: “This is not just insulting to the #BlackLivesMatter movement, it is deeply embarrassing for Dominic Raab.
“He is supposed to be the Foreign Secretary of the United Kingdom.”
Labour leader Keir Starmer said he thought Mr Raab would "live to regret" the comments, adding he suspected the foreign secretary was "wishing he hadn't said it".
Troy Townsend of the anti-racism football organisation, Kick It Out, said Mr Raab should not have shown his "own personal ignorance."
"I think it was clumsy and if you are going to be putting yourself front and centre you should actually know what you're talking about, don't make it a comedy act," Mr Townsend told ITV News.
"Don't show your own personal ignorance about something that you must know is of importance to so many people by demeaning. because people like me, people of my colour, people of an ethnic background have been demeaned for far too long now, to get politicians demeaning us in 2020 as well."
Labour former shadow home secretary Diane Abbott wrote: “Taking the knee began in 2016 with American athletes refusing to stand for US national anthem.
“They were protesting police brutality and racism. But @DominicRaab thinks it comes from Game of Thrones!!!”
When Kaepernick first took a knee he was ostracised by the NFL and has not played a game since 2016.
Football fans voiced their outrage at the player by burning his jersey, while US President Donald Trump even said players should be "fired" for disrespecting the flag.
Protesters in London have been seen taking the knee while demonstrating and maintaining safe distances, with marshalling police also taking part in a show of solidarity.
Footballers also took a knee at the restart of Premier League football on Wednesday night, with all four teams and the referees across the two matches doing so.
Mr Floyd's killing has sparked furious debate in the UK about whether statues which commemorate slave owners should be taken down.
Activist and model Munroe Bergdorf said Mr Raab's comments were "tone deaf" and "insensitive," adding the foreign secretary had shown his party was "wildly out of touch".
Mr Raab told ITV News he doesn't believe the UK should be "airbrushing" its history, after the governing body of an Oxford University college “expressed their wish” to remove a statue of Cecil Rhodes.
Rhodes was a British imperialist who founded Rhodesia, which is now Zimbabwe and Zambia.
Mr Raab said: "I think it's right there should be points of debate. I'd like to see us upgrade, refresh the symbols that we have for modern Britain."
Troy Townsend of anti-racism campaign Kick It Out said the comments were "clumsy".
"If you are going to be putting yourself front and centre you should actually know what you're talking about.
"Don't make it into a comedy act. Don't show your own personal ignorance about something that you must know is of importance to so many people by demeaning.
"People like me, people of my colour, people of an ethnic background have been demeaned for far too long to now, in 2020, get politicians demeaning us as well."
Mr Floyd died after a white police officer held him down by pressing a knee into his neck for almost nine minutes in Minneapolis on May 25.
Protests were sparked around the world after video footage showed Mr Floyd gasping that he could not breathe while being arrested by four officers.