The two companies are still in discussions over his exact start date.
Emap's previous chief executive, David Gilbertson, stepped down four months ago.
In 2010 Experian transferred its hosted database business, of which Sky was a customer, into a joint venture with Sky, which initially took a controlling stake and went on to buy Experian out.
Painter was made managing director of the business, which was named Sky IQ.
Earlier in his career he was chief executive of consumer data analysis company ClarityBlue. The company was acquired by Experian in 2006, and he went on to become global product leader at Experian Marketing Services.
Irina Hemmers, chairman of Emap and a partner at joint shareholder Apax Partners, said: "Duncan has extensive experience of leading successful B2B and data companies and was the stand-out candidate for the role."
In its previous nine-month reporting period to December 2009 it made £25m.