Külling was clear on his chosen career from an early age: he wanted to become a graphic designer. So he attended the preparatory course at what is now Zurich University of the Arts and undertook an apprenticeship in Gérard Miedinger’s Zurich studio. After completing his degree in 1956, his travels took him to Milan, where he found work with Franco Grignani.

On his return to Zurich, Külling was employed as a graphic designer at Victor N. Cohen’s advertising agency, which in those days had around ten employees. From it emerged Advico, one of Switzerland’s largest advertising agencies. After a short while, Külling was promoted to Creative Director, soon becoming a member of management and, in 1977, a partner in the business.

He also had many opportunities to gain experience in agencies abroad. In 1961, he worked briefly at the major London agency Ogilvy & Mather. In the early 1960s, when Switzerland began embracing television advertising, he went to Chicago to learn this work as well from Leo Burnett.

Advico merged with Young & Rubicam in 1988, at which point the agency for corporate design was renamed Külling+Partner Design. In 1996, Ruedi Külling and Hanspeter Hanschick, a watch- marketing specialist, founded the company Xemex Swiss Watch. As both an advertiser and a watch aficionado, Külling thus fulfilled his dream of developing the brand architecture of his own firm from scratch.

His advertising posters have been honoured 14 times by Switzerland’s Federal Department of Home Affairs. His advertisement for Bic won a first prize at the Cannes advertising festival, while Xemex was crowned ‘Watch of the Year’ in 2001 and 2002.

Külling has been a member of the Alliance Graphique International (AGI) since 1968.