Herriman will be responsible for overseeing Glue Isobar, Isobar Mobile and Isobar Social, and is charged with building on the company’s model of integrated business with digital at its heart.
She will report to Aegis Media’s UK chief executive, Rob Horler.
Her arrival will allow Mark Cridge, the founder of Glue Isobar, to concentrate more fully on his role as Isobar’s global managing director.
While at WCRS, Herriman oversaw its merger with the sister digital agency Altogether, creating WCRS&Co.
She said: "With agencies struggling to integrate genuine creative thinking and digital innovation, where better to crack it than Isobar with its pedigree of creativity and digital excellence."
Cridge added: "Securing the services of Penny is hugely welcome. She’s great at driving senior client relationships and has a real passion for creative work."