Cheshire Police said the 26-year-old from Cornwall was found collapsed in a campsite at the dance music event at Daresbury, near Warrington.
He was discovered at about midnight and emergency services were unable to save him, police said.
The four-day festival, which started on Thursday, includes performances from stars including Calvin Harris, Tiesto, Fatboy Slim and Pete Tong.
Police said formal identification was yet to take place and it was awaiting the results of the post-mortem examination to establish the cause of death.
A man has died after collapsing at the Creamfields festival.