Bright Light will run the UK press office and work closely with Invista to build the consumer and trade profile of the Lycra fibre brand.
The agency will work on the 'Choose Freedom' campaign, to highlight the brand's key messages of freedom, movement and comfort.
Paige Mengers, managing director of Bright Light, said: "We look forward to collaborating to drive strategic vision and building preference and likeability further."
Bright Light works with other fashion and lingerie brands including Fiorelli, Implicite and Seasalt.
At the beginning of the year the agency merged with fashion comms company MLPR, launching a beauty division and growing its travel sector.