The Marussia MR03 is a Formula One racing car designed and built by the Marussia F1 Team. It competed for part of the 2014 Formula One season, before the team went into administration in November 2014. Following the team's resurrection as Manor Marussia F1, the car raced as the MR03B after modifications were made to enable it to compete in, and meet the regulations in place for, 2015.

This was the first Formula One car to run on Valvoline lubricant since the Lotus 91 in 1982 despite the MR03 car's fuel was supplied by Shell V-Power.

The MR03 was driven in 2014 by Jules Bianchi and Max Chilton, both of whom returned to the team for a second consecutive season. The car was the first car designed by Marussia to use an engine built by Ferrari, the 059/3. In general terms, and compared to previous years' cars, the MR03 performed better relative to the opposition. In addition, with this car, Bianchi recorded his and Marussia's first points ever in Formula One at the Monaco Grand Prix.

After entering into administration in late October 2014, the team did not attend a race event for the first time in its history resulting, therefore, in the MR03 not being fielded at the United States Grand Prix. With the team folding in November 2014, the MR03 did not further participate in the 2014 Formula One season.