A right fielder, abbreviated RF, is the outfielder in baseball who plays defense in right field (e.g., "Roberto Clemente was a right fielder"). In the numbering system used to record defensive plays, the right fielder is assigned the number 9.

Outfielders must cover large distances, so speed, instincts and quickness to react to the ball is key. They must be able to catch fly balls above their head and on the run, as well as prevent balls hit down the right field foul line from getting past them. Being situated 250-300 feet from home plate, they must be able to throw the ball accurately over a long distance to be effective. Of all outfield positions, the right fielder should have the strongest arm, because they are the farthest from third base. Hits to right field tend to curve toward the right field foul line, and right fielders must learn to adjust to that.

Amateur players may find it difficult to concentrate on the game, since they are so far from the more continuous action. Emphasizing the correct starting position gives outfield players something to concentrate on at each pitch. The right fielder tends to be a stronger offensive player than defensive, as right-handed batters tend to pull the ball to left field. Exceptions, however, are common: Minnesota Twins Hall of Famer Kirby Puckett played right field as well as center for the last three years of his career.

As well as the requirements above, the right fielder backs up first base on all throws from the catcher and pitcher, and all bunted balls, since the catcher or the first baseman must be available for fielding the ball. The right fielder back ups second base on any ball thrown from the left side of the field, i.e. shortstop, third base or foul line territory.