Invest In Cornwall (IIC), a service of the council's Cornwall Development Company, is offering a two-and- a-half-year contract in an attempt to attract inward investment from foreign companies.
The new brief, worth up to £170,000, will see the chosen agency work with IIC's marketing team in Truro in an effort to drum up interest.
The move follows IIC reviewing its current agency work. The deadline for submissions is 11 May, with an agency expected to be in place by mid-summer.
Alison Elvey de Rios, interim project manager at IIC, said: 'We are looking for a dynamic PR agency that can provide a combination of creativity and local adaptability.'