The company called the move a "strategic decision". Spark44, which is part owned by Jaguar's owner Tata, will take on the account in May.
The shop is the communications agency for Jaguar and has handled creative work for the car manufacturer since 2011.
A spokeswoman for Jaguar said: "The strategic decision to transition the Jaguar social media services to Spark44 followed a review of the provision of those services."
Jim Coleman, the managing director at We Are Social, said: "Despite a long relationship of successful award-winning work with Jaguar global and UK, Jaguar Land Rover has chosen to cut costs by moving the work to its in-house agency."
Jaguar and Land Rover merged in 2008 after Tata Motors acquired the businesses from Ford.