In 1994, Rodriguez made his professional baseball debut as a minor league player with the Appleton Foxes of the Class A Midwest League. He was promoted to the Jacksonville Suns of the Class AA Southern League. He played in 17 games for Jacksonville, and was promoted to the major leagues. On July 8, 1994, Rodriguez was 18 years old when he debuted in the major leagues as a starting shortstop. He was just the third 18-year-old major league shortstop since 1900. He was also the first 18-year-old major league player in 10 years, and the youngest position player in Seattle history. Rodriguez recorded his first major league hit when he singled off of Sergio Valdez on July 9 at Fenway Park. Rodriguez played in 17 games for the Mariners, compiling a .204 batting average, two RBIs, and three stolen bases. The Mariners optioned Rodriguez to the Calgary Cannons of the Class AAA Pacific Coast League (PCL) in August. In 32 games for Calgary, he had 37 hits in 119 at-bats for a .311 batting average. He also compiled six home runs and 21 RBIs.