The media planning agency will provide strategy on media channel use and targeting new customers. ZenithOptimedia is retained as Lexus' media agency, but Trinity will work alongside it on bringing together its communications across digital, brand and DM.
Trinity is also expected to work with Lexus' wider roster of agencies, including Kitcatt Nohr and the data management agency Fuel.
Matt Button, the CRM and database manager of Lexus, said: "We appointed Trinity because of its proposition of unifying digital, brand and direct communications and moving away from conventional media silos."
Phil Nunn, a partner at Trinity, said: "Our aim is to encourage potential customers to engage with Lexus."
Trinity was launched last year by Nunn, a former Manning Gottlieb OMD director, Amy Lennox, also an ex-OMD director, and Simon Timlett, who held senior roles at Optimedia and Brand Connection.