She will work across all of the agency’s clients including Adidas, HSBC and Heineken.
Pinnell has been tasked with growing and developing We Are Social’s strategic offering. She will report into Mobbie Nazir, the chief strategy officer.
Pinnell replaces Jerome Courtial who left last year to set up his own agency called JCMT. He was named the head of strategy at We Are Social in 2013.
She joined AnalogFolk in June last year and helped the agency pick up clients such as Lucozade and Pandora.
Pinnell said: "I was particularly attracted by We Are Social’s approach to putting social thinking at the heart of everything it does – understanding social behaviours is now a crucial part of producing great work that resonates with consumers in any market and any sector."
Pinnell worked at J Walter Thompson as planning director between December 2010 and June 2014. Before this, she was a senior planner at Poke for three years, and a senior planner for Publicis Chemistry for seven months.
Her career also spans Partners Andrews Aldridge, Souk 360, Ogilvy & Mather, and Hall & Partners.
Nazir said: "Lise is a very talented strategist who has really made her mark on the digital landscape over the last few years.
"She’ll lead our strategy team into the next stage in its evolution, as the driving force behind the delivery of creative work that proves the value of a socially-led approach."