The agency will start work immediately. Managing director Nadia Gabbie will lead the account and report to WeTransfer owners Bas Beerens, Damian Bradfield and entrepreneur Nalden.
The six-figure retained business will be handled by 77PR in the UK and parent company Fishburn Hedges in the US. The international brief is to increase WeTransfer's user base and introduce the service to potential new users across the globe.
In addition to consumer-facing work, the agencies will aim to raise awareness of the service among the creative industries.
Last month, WeTransfer announced it had reached the milestone of hosting more than 1.5 million transfers a day. Since launching in 2009, the business has achieved 127 per cent year-on-year growth, claiming 15 million monthly active users worldwide.
The Amsterdam-based company was set up by design consultancy owner Beerens and lifestyle blogger Nalden as a means to distribute photos, video content and other documents quickly, and save on courier costs.