He is quitting the role without a job to go, but will be staying in Amsterdam to pursue other career opportunities.
StrawberryFrog is in the process of interviewing for a replacement. In the meantime, the executive creative director, Al Kelly, will lead its creative department.
Formerly with HHCL, Chalmers joined StrawberryFrog in 2000 as its creative director. He was initially responsible for launching BlueberryFrog, the guerrilla marketing arm that was merged into the main agency in 2004.
During his seven-year stint at the agency, Chalmers worked on clients including Mitsubishi, Ikea, Sony Ericsson and Heineken.
Chalmers said: "There's a lot of change within the industry and that is creating continuous opportunities. I'm leaving to investigate some of those opportunities."
He added: "I'll most definitely retain a relationship with the founders, as it's been such a hugely inspirational part of my career."