At Adecco, Yallop takes charge of marketing across its various recruitment divisions -- Adecco Retail, Adecco Enterprise, Office Angels, Computer People, finance arm Jonathan Wren and engineering recruiter Roevin.
She will work closely with Annalisa Gigante, Adecco's recently appointed global chief business development and marketing officer.
At Rentokil Initial, Yallop worked in its business support services and facilities management division, where she was director of strategic development and marketing until December.
Yallop said: "There are some great challenges and opportunities currently facing the industry and Adecco will continue to be at the front of forward thinking in our sector."
Adecco started 2008 by appointing LBI as its full-service digital agency.