A security guard who allegedly bashed a man who spat on him at a hotel in The Rocks, has been charged by police.

Police said the male security guard, 27, escorted the 48-year-old victim from a hotel on George Street, in Sydney, about 9pm (AEDT) on Friday.

Once outside, the man allegedly walked back to an entrance of the hotel and spat on the security guard.

Police allege the security guard followed the man down the street and punched him in the face, before also assaulting another man who tried to intervene.

The security guard has been charged with affray, assault occasioning actual bodily harm and common assault, police said in a statement.

He was granted bail and will face the Downing Centre Local Court on January 29.