Speaking to CNBC, Sorrell said that WPP would spend $200m (£153m) on Snapchat – twice as much as last year – but that compared to what it would commit to Facebook it was still at a very low level.
Last year WPP spent about $1.7bn on Facebook but told CNBCs Squawk Box that this year it will be "well over" $2bn.
Nonetheless Sorrell told the programme that he still likes Snapchat over Facebook. "I think [Snapchat] is potentially more competitive as the third force."
Snapchat owner Snap has faced pressure from Facebook's Instagram, which last year replicated its Stories feature allowing users to share photos and videos to their followers, which then expire 24 hours after they were posted.
Sorrell also spoke about social media companies fighting the rise in extremist content and said that Facebook and Google are making significant steps but must be "vigilant as you possibly can".
This article first appeared in PRWeek sister title Campaign