on december 2, 2002, he was traded along with mark grudzielanek to the chicago cubs in exchange for todd hundley and chad hermansen. karros started the season as the cubs backup first basemen, but took over the role at the beginning of june after hee-seop choi was injured in a collision with cub teammate kerry wood. after playing the season with the cubs he was granted free agency from the team at the end of the year. in 114 games with the cubs, he hit .286 with 12 home runs and 40 rbi.