The UK-listed pharma firm has shifted its PR account to Roland Rudd's City agency from arch rival Brunswick.
Finsbury beat a host of City PR firms to secure the brief, with only Maitland and FD thought to be conflicted due to their work with GlaxoSmithKline and Shire Pharmaceuticals respectively.
It is thought that Brunswick repitched unsuccessfully.
AstraZeneca's head of global media relations Esra Erkal-Paler confirmed to PRWeek: 'Following a competitive pitch process, AstraZeneca has appointed Finsbury as its retained corporate comms consultancy.
'As well as advising on financial comms, Finsbury will support AstraZeneca's ongoing efforts to build its corporate reputation.'
A key issue for Finsbury will be assuaging fears in the City over AstraZeneca's product pipeline. The firm faces patent expirations of a number of its major drugs, with US regulators considering whether to approve vital new medicines.
Analysts suggested sales of the firm's anti-clotting drug, Brilinta, alone could top $1bn by 2015 if approval is granted.
Finsbury partners Andrew Dowler and Conor McClafferty will lead the account, reporting to Neil McCrae, vice-president group corporate comms, and Erkal-Paler, who are both based at the company's global headquarters in Paddington, London.
PRWeek first revealed AstraZeneca was repitching its financial comms account in early June (prweek.com/uk, 2 June).
Meanwhile, it is understood Brunswick has been taken on to handle ITV's financial and corporate comms. It is thought the agency picked up the account without a pitch, having built relationships with ITV's CEO Adam Crozier and new comms director Mary Fagan while the pair were at Royal Mail. ITV previously used Tulchan Communications.