The council will pay up to £350,000 over three years to provide consumer PR, media relations and stakeholder relations for the £187m 'world-class new cultural destination', scheduled for opening in summer 2013.
A spokesman for Birmingham City Council said: 'Since 2008, the comms campaign for the Library of Birmingham has successfully gathered pace, generating interest, enthusiasm and excitement for the project across media and stakeholder groups at local, national and international level.'
The council now wants to appoint a PR agency to deliver the next stages of the comms campaign, including media relations, PR, marketing and stakeholder engagement, through to the immediate post-opening period.
A shortlist for face-to-face pitching is being drawn, with the successful agency starting work in January.
The library, which has been designed by international architects Mecanoo, will be integrated within Birmingham's Repertory Theatre.
An independent charity, The Library of Birmingham Development Trust, will raise funds to complement Birmingham City Council's investment.