The campaign is to launch before Christmas and will focus on recruiting both new triathletes and converting those who already have a relationship with the sport.
It will include content development and a digital influencer programme, with a video featuring a broad range of triathletes set to be the first piece of activity.
Jo Simpson, commercial director at British Traithlon, said: "As soon as we started talking with The Playbook it was clear that they understood our objectives. They approached the brief with a strong focus on insight and creativity, resulting in a campaign that we’re really excited to get started on."
Eddie May, MD of The Playbook, said: "We were all very excited to see such a strong showing from British Triathlon’s elite athletes out in Rio and now there is a clear opportunity to engage the wider triathlon family to make sure that momentum is not lost."
The Playbook, which focuses on sport, active health, wellbeing and technology brands, was launched by Hanover in July. Group CEO Charles Lewington said at the time that the launch "enables us to become a full-service communications group that delivers for the most exciting brands on the global stage".