The agency will handle launches in New York and London with the help of Team GB Olympic boxing gold medallist Anthony Joshua.
Diffusion will lead a grassroots influencer programme after winning a pitch for the brief, previously held by Four Communications.
The brand shares its profits with Fight for Peace, an expanding charity originally set up in Brazil to encourage young people from deprived areas to take up boxing.
Diffusion will back the launch with a programme of brand ambassador engagement, targeting bloggers and influencers in the fitness and ethical consumer spheres.
This will be supported by a media and product-placement campaign to establish Luta’s presence in the fashion and lifestyle press.
Diffusion head of consumer Tom Malcolm said: ‘Luta’s influencer campaign is indicative of the awareness clients have of the need to engage with an international audience and create movement around a campaign.’