In his new role Cromack will oversee the strategy and development of standardised cross-selling procedures for the group's broad range of products and services.
Cromack said: "It's a very interesting time for all companies in this sector and there are some clear challenges ahead of us over the next couple of years especially.
"However, challenges present great strategic opportunities for those who tackle them head on and I am very excited about leading o2o's managed services business development drive into 2010."
Cromack's promotion marks a continuation of the board's declared strategy of leveraging o2o's BPO capability to boost its standing as a managed services business.
Simon Moate, chief executive of o2o, said that the group's diverse portfolio of products and services meant that there was "huge scope for growth" through cross-selling.
He added: "Jason brings with him to the role tremendous senior level industry experience. As chief executive of TripleArc and then AccessPlus, he was very adept at finding new revenue streams and developing innovative services to grow the businesses, and we are looking forward to him now utilising these skills right across the o2o group."
Meanwhile, o2o has also announced that chief operating officer Steve McKeever will assume responsibility for all business critical services divisions in the group including AccessPlus and Banner Document Services as well as overseeing the group's supply chain management.
The o2o group acquired AccessPlus in a £26m deal in May 2008.