Demonstrators from animal rights group DxE Brighton, members of the international Direct Action Everywhere, entered the Brighton London Road restaurant last night (May 17), wearing animal masks and brandishing placards.
Several protesters used megaphones to get their messages across - that 'it's not food, it's violence' - to staff and customers eating at the chain.
"Born to be murdered, their flesh sold for profit," said one protester.
"These are babies who feel fear and pain and seek comfort, like we all do. A cruel, violent and greedy system must be challenged. Who are we if we allow innocents to die? If we value, money, taste and convenience over life itself?
"The power we have over our fellow animals is not an invitation to exploit. Might is not right."
One member of the group covered the windows and floor of the restaurant in fake blood for added affect.
A spokesman from DxE said police arrived on the scene within 15 minutes and asked the activists to leave - who all complied except one.
The remaining protester was handcuffed and removed by three police officers, said the spokesman.
A picture from the scene shows a female being carried horizontally by three police officers, towards a waiting police van.
A spokesman for McDonald's confirmed the incident took place at the London Road restaurant.
"Due to the mess and damage caused, the restaurant was closed from 7:30pm whilst the team worked hard to return the restaurant to normal and we reopened at 5am today," said the spokesman.
"We are supporting the police with their ongoing investigation and apologise to any customers adversely impacted by this incident.”
Sussex Police have been approached to confirm if any action was taken against the demonstrators.