The 45-year-old musician, who performs under the pseudonym Fatboy Slim, checked into a clinic in the south of England on Monday, reports The Mirror.
His manager Garry Blackburn said: "It's all pretty straightforward. He has gone in voluntarily to sort out his drinking problem."
Cook, who is married to Zoe Ball and has a nine-year-old son Woody, apparently arrived at the rehab centre on Monday dressed in a checked shirt and baggy tracksuit bottoms.
The DJ has previously denied allegations that he entered rehab in 2002, describing the reports as "utter s**t".