Simon Collister was until last week head of digital for the agency's consumer practice.
Weber Shandwick Consumer MD Scott Wilson, to whom Collister reported, said the agency would replace Collister, but added that it would seek a different range of skills.
'Simon Collister has left Weber Shandwick Consumer by mutual agreement,' said Wilson. 'Going forward, our commitment to providing a dedicated, creative digital resource to our clients remains undiminished.'
Collister moves to social media agency We Are Social to head the charity/non-profit practice, reporting to MD Robin Grant and managing partner Nathan McDonald.
Collister joined Weber Shandwick from Edelman, where he was head of digital culture and emerging media. He was the first standalone digital hire made by one of the agency's practice groups. Weber Shandwick already has a digital division led by James Warren, who said the agency remained committed to 'embedding digital talent in the practice groups'.
However, an industry source noted that the revenues may not have supported Collister's role within the consumer team: 'There is a big challenge around monetising what digital does - maybe the money for standalone digital stuff wasn't forthcoming in the consumer space.'