Cogent Elliott won the brief after a four-way pitch. It is a new brief for the company and follows the appointment of Neil Morley to the role of head of brand communications and dealer development.
Previously Triumph worked with various agencies across its international markets, but global expansion has lead to a need for a better defined brand and more marketing infrastructure.
Triumph concentrates its marketing spend on digital and print advertising, as well as experiential marketing and dealer sales support.
Cogent Elliott will advise on global brand development and creative across all Triumph's marketing communications.
The appointment comes ahead of the launch of a brand new model for Triumph -- a cruiser known as the Thunderbird.
The motorbike will be launched in the summer in all Triumph's international markets.
Paul Stroud, director of sales and marketing at Triumph, said the agency had been appointed at an important stage in the company's development.
Stroud said: "Their combination of brand and customer insight, strategic planning, creative excellence and breadth of offer, along with their comprehensive experience of global launch planning, makes them the perfect partner for us at this exciting time."