The insurance giant has used ZenithOptimedia, which will soon rebrand to Zenith, since 2010 and carried out the "open market" review as part of a "standard procurement process" to ensure it is getting value for money.
The account covers six main markets – the UK, Ireland, Poland, France, Singapore and India.
It is an important account retention for ZenithOptimedia's parent company, Publicis Groupe, which recently reorganised all its media agencies in a single division, Publicis Media.
Mark Howley, the UK chief executive of ZenithOptimedia, said: "Aviva has a very clear view of where they're going and we're delighted to partner with them."
The UK is the FTSE 100 company's most important market where it sponsors rugby’s Aviva Premier League.
An Aviva spokesman said: "Aviva has renewed its global media buying contract with ZenithOptimedia for a period of three years from July 2016 following a rigorous tender process. Aviva has a long and successful relationship with ZenithOptmedia and the new contract will reflect Aviva’s evolving marketing strategy in its global markets, particularly in the areas of digital investment."
It was previously thought the account was worth about £60 million but it is understood that it is now closer to £100 million, including search.