Police were called shortly after 1pm and made four arrests for public order offenses and breaches of coronavirus virus legislation.
Photographs taken just after 5pm show that hundreds of young people stayed outside the store during this time.
Many did not appear to be socially isolated despite the coronavirus pandemic.
The group eventually dispersed following instructions from the police.
In a statement Metropolitan police said: “Police were called around 13: 09a on Saturday, December 5 to reports of a large group of people trying to get into a shop in Brompton Road, SW1.
“Four men were arrested in total – two for charging, one for violating Covid’s regulations, and another for a public order offense and a breach of Covid’s regulations.
“The crowd has dispersed ever since.”
Viewers took to social media to describe their shock at events.
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One Twitter user asked: “Harrods what the hell is happening ??
“We ended up leaving the shop because of the f ** king chaos inside and out.
“Not wearing masks and not being challenged ??? #COVIDIOTS. ”
Another added: “If anyone is thinking of getting close to Harrods Knightsbridge don’t.
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“It seems like riot police everywhere.”
There were also reports on social media of disorder outside the Harvey Nichols store in Knightsbridge.
London is currently restricted to tier two coronavirus.