Duffy signed a minor-league contract with the Rangers on Thursday and received an invitation to major-league spring training.
Duffy elected free agency in November after slashing .251/.306/.325 across 209 plate appearances with the Royals last season. The 33-year-old infielder won't see many starts with the defending World Series champions, but his defensive versatility and ability to maintain a decent batting average could allow him to win a spot on the Rangers' bench during spring training.