The agency won the business after a pitch, which kicked off at the end of last year and was led by Jennifer Horner, the global marketing director for Aviva Investors.
CMW will now be responsible for developing a global positioning and brand strategy for Aviva Investors that will launch in the first quarter of next year and will run across the brand's core European, North American and Asian markets.
The work is expected to predominantly incorporate press, outdoor, digital and direct marketing executions.
CMW's appointment marks the first time that Aviva has used an agency to work on global campaigns specifically for its investment arm.
In the UK, the brand works with a number of agencies, including Abbott Mead Vickers BBDO, The Gate, Proximity London and Chemistry.
Its media planning and buying agency is ZenithOptimedia, which was awarded the £150 million global business in January.
Aviva launched its investment arm in 2008, bringing together a number of regional asset management companies. The division has more than 1,000 employees and offers businesses a range of options such as pension schemes and bonds.
Horner said: "We have a real desire to create a strong point of difference for our brand and communications. CMW will play a pivotal role in supporting us on this journey."