Citigate will be charged with attracting non-EU businesses into Cornwall and promoting it as an international business centre in key sectors.
The agency is thought to have secured a two-and-a-half-year contract, worth up to £170,000, following a competitive pitch process.
Citigate will develop a PR and social media programme, as well as running showcase initiatives targeted at challenging the perceptions of Cornwall.
The agency will particularly look to highlight the county’s growing presence in the international aerospace, renewables and technology sectors.
Cornwall is currently benefiting from a £445m EU ‘Convergence’ investment programme, which is helping to improve transport, workspace and infrastructure.
Since 2004, Cornwall's inward investment agencies have helped more than 130 businesses to invest in Cornwall, including Lockheed Martin UK, Check My File and Fugro Seacore.
Citigate will report to Lucy Hunt, manager of Invest In Cornwall for Cornwall Development Company.