He played in Major League Baseball (MLB) for the Philadelphia Phillies, St. Louis Cardinals, Pittsburgh Pirates, and Chicago White Sox.

Signing with the Cards as a free agent in 1985, LaValliere spent two years with the club, which included a trip to the World Series.

In spring training of the 1987 season, LaValliere was traded to the Pittsburgh Pirates alongside Andy Van Slyke and Mike Dunne in exchange for fellow catcher Tony Peña.

LaValliere and Van Slyke later became stalwarts on the hugely successful Pirates teams of the early 1990s, when Pittsburgh went to three consecutive National League Championship Series from 1990 to 1992.

The White Sox won the American League West division title, but lost in the ALCS to the eventual World champion Toronto Blue Jays.