The appointment puts an end to Partners Andrews Aldridge's six-year relationship with the car brand, which began in 2001 when the agency scooped the business in a three-way shootout.
Kitcatt Nohr will now take on responsibility for the car brand's prospect and customer management campaigns, which will seek to nurture relationships with existing customers as well as driving sales to prospective consumers.
The campaigns will run across both direct and digital channels.
The management of Lexus's data will remain with the incumbent data agency Fuel.
Matt Button, the CRM and database manager at Lexus, said: "I have nothing but respect for the work Partners have done over the last six years. We felt the time was right to review our strategy and our agency and we were bowled over by the coherence, creativity and gravitas of the Kitcatt Nohr team."