Harrison joins the car company in the newly-created role after nine years at rival car firm BMW.
McLaren Automotive is building the next generation of its own branded supercars to rival Ferrari, Lamborghini and Aston Martin. Harrison has been brought on board to head up the PR function and is charged with recruiting a small global team. He will also organise global events including motor shows and press launches as part of his role.
He reports in to sales and marketing director Rob Lindley.
The company's debut vehicle, the McLaren F1 road car, was produced in 1994 and was until recently the fastest-ever production road car after achieving a speed of 240mph.