The city was overwhelmed by party goers on Saturday, after an estimated 250,000 people turned up for an open air party hosted by the star.
The fatality and a number of injuries occurred as fans packed onto the beach and promenade between Brighton's two piers, forcing ambulance crews to take to lifeboats to rescue casualties.
The free event, called the Big Beach Boutique, had been expected to attract just 60,000 people to the seafront.
A man in his 40s died on the beach after suffering a heart attack at about 2200 BST on Saturday evening.
A 26-year-old woman remains critically injured after she fell from railings onto the lower esplanade at about 0120 BST on Sunday morning.
A spokesman for the Royal Sussex County hospital described the situation following the event as "a nightmare", and said resources were stretched to deal with 90 casualties.
Thousands of people were left stranded in Brighton for hours overnight, roads were blocked and there were chaotic scenes at the city's railway station.
The Big Beach Boutique concert had been billed as Europe's biggest free beach party.
Fatboy Slim, who is married to TV presenter Zoe Ball, spent £100,000 of his own money supporting the event after a major sponsor pulled out.
But the huge crowd almost overwhelmed emergency services.
Sussex Ambulance Service said the size of the crowd meant it had to call in Brighton's lifeboat crew, to ferry revellers in need of medical attention to Brighton Marina.
Injuries
The service said it was easier to travel by water than to get an ambulance through the tens of thousands of revellers.
Police have appealed for witnesses to the woman's fall from the upper to the lower esplanade.
Other revellers were treated for minor problems such as crushing, though a police spokesman said some of the casualties were victims of assaults which were "mostly the effects of high spirits".
Police chiefs and council leaders are now planning urgent talks about how the event became so massive.
A Sussex Police spokesman said: "This was the biggest event Sussex has ever seen and lessons will be no doubt be learned.
'Awful'
"No one expected those sorts of numbers. I am sure there will be many meetings to discuss the future of the event."
Steve Tilling, a senior control centre manager for Sussex Ambulance Service, said: "With hindsight, it would be easy to say it was awful and should never have happened.
"But we are lucky in Sussex to have places where we can hold such events and I think generally they should go ahead.
"But I think we now need to approach this event on the side of caution and look at ways of somehow limiting numbers."
Meanwhile Fatboy Slim - aka Norman Cook - promised extra funds to pay for the clean-up operation, not expected to end before Monday afternoon.
The DJ said: "This was without doubt the biggest gig of my career. Brighton has responded superbly. I would like to thank the emergency services on the night and everyone involved in the clean-up operation.
"We now have to return the city I love to how it should be seen."