Trethewey held the position of director of business innovation for Europe within Fuse, the branded entertainment and sponsorship unit of media agency OMD.
The role was pan-European in focus, and involved driving increased understanding and investment by OMD clients beyond the traditional six channels of media, with a primary focus on music.
He joins Frukt as it moves its focus more to brand and music partnerships following an increased demand from brands wishing to work more deeply with music and to exploit the commercial benefits of music partnerships.
His remit is to grow the music and brands division, working with brands and their PR agencies to devise ways in which they can use music as an effective marketing tool.
Frukt is also making changes to its music industry market research and consultancy business, which it has rebranded as Frukt Music Intelligence (FMI).
It is decommissioning the monthly magazine published by this side of the business, Five Eight, but will produce a daily news bulletin, a bi-monthly report on key trends in the industry, two annual special reports and access to regular subscriber events and networking opportunities featuring marketing and music luminaries.
Jack Horner, joint managing director and creative director of Frukt, said: "The old models for monetizing recorded music are visibly struggling, yet there's never been a time in history when so many people have enjoyed so much music in such a vast variety of ways.
"While traditional approaches become less relevant, consumer brands and technology companies have an opportunity to step in and help shape entirely new ways of getting music from creator to fan, and to play a key part in the broad cultural space of music.
"With Frukt's expertise and depth of knowledge in this arena it was imperative for us to respond to the changes in the industry.
"By refocusing a major area of our business we are able to offer brands a more comprehensive way of engaging with music and trends in the new music landscape."