Williams, who never announced his retirement after New York let him go in 2006, went 1-for-3 and struck out once as Gigantes de Carolina defeated 4-1 Indios-Tiburones de Mayagüez-Aguadilla at the Roberto Clemente Walker Stadium.
This is the first step as the 40-year-old outfielder tries to get back into the game in hopes of joining Puerto Rico's squad in next year's World Baseball Classic.
"The team took him in immediately since Bernie started training with us," Carolina manager Jose "Cheíto" Oquendo said. "They recognize Bernie as a legend. It's good to see him in uniform."
Williams, who batted second in the lineup as DH on Monday, didn't play winter baseball in his native country since his stint with Arecibo in the 1995-96 season.
As New York's center fielder from 1991-2006, Williams made five All-Star teams, won four Gold Gloves and was selected MVP of the 1996 AL Championship Series. He turned down the Yankees' offer of a minor league contract to come to spring training in 2007.
Information from AP was used in this report.