To make room on the 40-man roster, right-handed pitcher Scott Carroll was designated for assignment.
LaRoche,35, who batted .259 with 26 home runs and 92 RBIs last season, will make $12 million in 2015 and $13 in 2016. He has 243 home runs over with 838 RBIs over 11 seasons.
“Adam’s signing addresses several important needs for our club heading into the 2015 season,” general manager Rick Hahn said in a statement. “He provides a proven left-handed bat in the middle of our lineup, brings a valuable mix of the ability to get on base and power, and he is a veteran leader on the field and in the clubhouse.”
LaRoche’s father Dave was a former major leaguer, who also served as a White Sox coach from 1989-91. His brother Andy played in the major leagues from 2007-13.