He attended Haverhill High School in Massachusetts, where his athletic abilities quickly became evident. Following high school, he enrolled at Wright State University in Ohio, where he began to focus seriously on baseball.

Collegiate Baseball and Early Career

Though he did not complete his college education, Peña made a strong impression in collegiate baseball. He played in the prestigious Cape Cod Baseball League, where he led his team with outstanding performances and emerged as one of the league’s top players. His success caught national attention, and he was featured in Baseball America's list of Top 100 Prospects.

In 1998, Carlos Peña was selected in the first round of the MLB Draft by the Texas Rangers. He began his professional career and steadily advanced through the minor league system.

MLB Debut and Rise to Prominence

Peña joined the Oklahoma RedHawks, the Rangers' Triple-A affiliate, in 2001. There, he posted a batting average of .288 and hit 23 home runs, further boosting his reputation. In 2002, he made his Major League Baseball debut, playing briefly with the Texas Rangers before being traded to the Oakland Athletics.

With the A's, Peña began to solidify his position in the majors. Although his time with Oakland was relatively short, he continued to develop his skills. His most notable early career period came during his stint with the Detroit Tigers, primarily in 2004, when he had one of his most productive seasons.

In 2006, Peña signed with the Boston Red Sox. His time in Boston was brief and not particularly impactful, leading him to seek other opportunities. He joined the Tampa Bay Devil Rays (now Tampa Bay Rays) in 2007, where his career experienced a major resurgence.