The inshore lifeboat crew pulled the woman out of the water and took her back to the lifeboat station to check her over and warm her up, an RNLI spokesman said.
The Coastguard also assisted.
Later the same day, the Coastguard was called to assist Sussex Police in a couple of beach searches for missing persons, a spokesman said.
This morning at 1.36am, the Coastguard was called to reports of a person underneath Brighton pier ‘clinging to the iron works’, according to the spokesman.
Brighton RNLI recovered the casualty who was handed over to the care of the ambulance service.