Rodriguez and his family moved to his father's native Dominican Republic when Alex was four, but they later relocated to Miami, Fla. There he became an excellent ballplayer at Westminster Christian High School, and in 1993 the Seattle Mariners selected Rodriguez as the first overall pick in the Major League Baseball draft. He made his debut with the Mariners at age 18, playing shortstop.

Rodriguez's first successful season came in 1996, when he accumulated a league-best .358 batting average with 36 home runs and 123 runs batted in. Over the next six seasons with the team, he continued to produce outstanding offensive statistics, most notably in 1998, when he became the third player in league history to hit 40 home runs and steal 40 bases in the same season. Before the 2001 season, when Rodriguez was a free agent, the Texas Rangers signed him to a 10-year $252 million contract, the richest contract ever given to an athlete at the time.

With the Rangers, Rodriguez continued to have great offensive seasons. He won Most Valuable Player (MVP) honours in 2003 with a .298 batting average, 47 home runs, and 118 runs batted in. After that season, he was traded to the New York Yankees. In 2005 he posted a .321 batting average, with 48 home runs and 130 runs batted in, to win his second MVP title. At Yankee Stadium on Aug. 4, 2007, at age 32, Rodriguez hit his 500th career home run, becoming the youngest player to accomplish that feat. The 2007 season was Rodriguez's best yet—he had a .314 batting average, with 56 home runs and 154 runs batted in—and he was named MVP for the third time. In addition to his MVP and other awards (such as the Silver Slugger and the Gold Gloves), Rodriguez was also a fixture at All-Star Games (All-Star Game).