Romero began his professional baseball career in the Milwaukee Brewers' minor league organization, playing for the Class A Burlington Bees in 1976.

In 1977, he played for the Double-A Holyoke Millers and also made his MLB debut with the Brewers, appearing in 10 games with a .280 batting average.

He played in one postseason game with the Brewers, during the 1981 American League Division Series against the New York Yankees, going 1-for-2 at the plate.

[1][2] Romero was traded by the Brewers to the Boston Red Sox in December 1985 in exchange for pitcher Mark Clear.

Romero spent part of four seasons with the Red Sox (1986–1989), appearing in 219 games while batting .241 with two home runs and 42 RBIs.

[1][3] In 1991, Romero appeared in 28 games for the Triple-A Las Vegas Stars, a farm team of the San Diego Padres.