The digital agency won the business after a four-way pitch against undisclosed agencies, which was called in June this year.
The company does not currently have a retained agency on the account, instead working on a project-by-project basis.
Brand Advocate has been tasked to develop the gin brand's customer relationship marketing strategy, working across all digital platforms, from point of sale to events, social mobile and online.
Until now, Hendrick's Gin's marketing activity has been largely experiential.
In January, the brand kicked off an "adventure-themed" marketing campaign, giving consumers the opportunity have afternoon tea with "a legend of adventure", such as Sir Chay Blyth, the round-the-world yachtsman.
LBi has undertaken digital work for the brand in the past, and, earlier this year, launched a social CRM campaign, developing a ‘Hendrick’s Curiositorium’ site to brand drive loyalty among premium gin drinkers.
LBi is understood not to have pitched for the business.
Hendrick’s Gin's current brand positioning is "a gin made oddly", with the juniper-flavoured drink being distilled in Scotland and manufactured in a dark-brown apothecary-style bottle.
Other William Grant & Sons brands include Glenfiddich and Grants.
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