The company will specialise in restructuring and realigning businesses that are media-centric - with a view to improving their structure and profitability.
Xsequor is a three-way partnership between Allen, McCulloch and ex- legal director of ITV, Kyla Mullins. McCulloch said Xsequor had a large network of senior individuals it can call upon to potentially expand, depending on the success of the project.
He added: "Our main difference [compared with other media consultancies] is we have all hired consultants ourselves and seen what works and where the gaps are. Xsequor is operated by senior managers who have all delivered big changes in business.
"Our specialism is looking after organisations with brands, intellectual property and a people culture - not manufacturing and not as narrow as just media companies. Many organisations behave like media companies - such as certain charities."
Allen, since leaving ITV in August 2006, has a accepted a string of directorships including: chairman of Global Radio, non-executive chairman of EMI Music, non executive director of Endemol and sits on the board of cable group Virgin Media - as well as becoming an adviser to Goldman Sachs Capital Partners.
McCulloch, who left ITV in May 2007, has since been operating as a freelance consultant as well as sitting on the Digital Britain Steering Board.