The agencies have been awarded three-year contracts for individual projects.
'Our objective is to identify new business opportunities, support and maintain revenue, provide thought leadership and research customer needs,' said OS chief press officer Scott Sinclair.
The previous three-year incumbent was integrated comms consultancy Proctor and Stevenson.
Targets are expected to include the manufacturers of wireless devices and global positioning systems, licensed mapping firms that use OS data, and consumers.
Although OS is a government agency, it covers its own operating costs.
As well as making maps, it provides digital geographical data.
For the first time this year it will have to pay a dividend to the Treasury of around five per cent of its profit. Last year OS made a £5.6m profit on turnover of £100m.