Conservative councillor Davis was chosen as Kingston Council leader at a party meeting last night after his predecessor Howard Jones stood down due to illness.
Davis' selection to the role follows the party wrestling control off the Liberal Democrats in last week’s local elections, ending 12 years of Lib Dem power.
In a statement released on its website, Cratus said: "In line with our company policy and desire to prevent any conflict of interest we will honour existing commitments, but will no longer accept any more work in connection with the Royal Borough.
"We wish Kevin well in working with his new councillor colleagues in serving Kingston residents over the next four years."
Davis, who is listed as having been involved in the launch of Cratus in 2009, had been elected to represent the Old Malden ward after losing his seat in 2006.
A spokesman for Kingston Council confirmed Davis’ role at Cratus, while Davis has not yet responded to a request for comment.