The Jaguar R4 is a Formula One car with which Jaguar Racing competed in the 2003 Formula One season. It was driven by Mark Webber, Antônio Pizzonia and Justin Wilson.

After three years in Formula One, and amid a turbulent atmosphere that had claimed the leaderships of Niki Lauda and Bobby Rahal, Jaguar Racing became much more stable in 2003. The car was also revamped, with the R4 representing a fresh approach compared to the previous season's R3.

At the Brazilian Grand Prix Webber crashed heavily, triggering an incident that led to the race being red flagged. Webber's commitment and determination was a boost to the team, recording several sixth- and seventh-place finishes en-route to a Constructors' Championship finish of sixth. Pizzonia lagged far behind, despite his experience and the car's performance as demonstrated by Webber's results.