The only baseball game released for the PlayStation in 2002, MLB 2003 continues Sony's seven-year franchise with updated teams, schedules, and rosters to reflect the beginning of the 2002 season. Eight modes of play include Quick Start, Exhibition, All-Star Game, Season, Playoffs, World Series, Spring Training, and Home Run Derby. The Season mode supports one or two players and offers both a Franchise and Manager option to further customize the action.

Instead of spanning multiple seasons in length, the Franchise mode in MLB 2003 involves earning points as a weakened club to acquire new, higher quality players. There are no trades in this mode, only additions and cuts. Each win and offensive statistic in the categories of home runs, triples, doubles, and stolen bases earns players points, while losing games deducts points from a player's talent pool. Manager mode has the computer playing the games based on decisions made in starting lineups, pitching, and fielding positions.

MLB 2003 also features a number of General Manager options, including trades, signing free agents, the ability to call up seven prospects from the farm system, and monitoring the disabled list. Players can also conduct a 25-round draft with adjustable salary cap limits, create up to 24 athletes, and shuffle the teams around the divisions by rearranging them manually or having them randomly reassigned. The cursor-based batting and pitching interface is identical to previous games in the series, and broadcasters Vin Scully and Dave Campbell once again handle the commentary.