The man, who has not yet been named, was attended by members of the emergency services in the early hours of Saturday at around midnight. However, they were unable to save him.
A spokesperson for Cheshire Police confirmed on Saturday: "Last night we were notified following concerns for a man in one of the campsites and, sadly, a 26-year-old man from the Cornwall area passed away." He added that formal identification had yet to take place and that the force's "thoughts are with his family at this time".
Though a post mortem would take place to establish the cause of death, the police spokesperson warned they remained vigilant about supply of illegal drugs at the festival at Daresbury. He said of festival goers: "We want them to have a great time, but do so safely.
"Officers continue to take positive action against those who risk others' lives by attempting to bring illegal drugs onto the site.
"The constabulary wants to remind people that drug supply at Creamfields will not be tolerated, and officers will take robust action where necessary."
The festival, which will be headlined by the likes of Calvin Harris, Tiesto and Fatboy Slim, began in 1998, is not the first to have seen fatalities this year. Ten days ago teenager Livvy Christopher died at Boomtown festival in Winchester. Paramedics attended the 18-year-old from Buckinghamshire, who was found in her tent, but were unable to revive her.
Speaking after the event a spokesperson for Hampshire police said: "Sadly, despite efforts from paramedics and the on-site doctor, she was pronounced dead at the scene.
"The death is not being treated as suspicious but investigations are ongoing on behalf of the coroner.
"Officers continue to work closely with BoomTown organisers and witnesses and friends who were at the event are being supported."
Creamfields takes place over the August bank holiday weekend, starting on 25 August and running until 28 Sunday.