Founded in China, the global firm provides app market intelligence to businesses such as Google, Zynga, Disney and Electronic Arts.
It is the first time App Annie has called in agency help in the region as it seeks to become "the Nielsen of apps" and expand its portfolio of products.
Positive Marketing will position App Annie as a leader in app analytics and a key voice on app trends across sectors such as games, music and books, with a focus on business and marketing titles, as well as creating content for the brand.
The agency will work closely with App Annie’s San Francisco-based VP of global corporate comms Marcos Sanchez, and EVP of marketing Oliver Lo.
Bateman Group will continue to handle App Annie’s PR in the US.
The four-year-old start-up, which tracks more than 33 billion app downloads across iOS and Google Play, secured $15m investment in a series C funding round led by Sequoia Capital towards the end of last year.