Sampson is set to join the Lotte Giants following the move announced Monday.
He went 6-8 with a 5.89 ERA in 125⅓ innings over 15 starts and 20 relief appearances for the Rangers last season, when he was one of seven big league pitchers with at least 15 starts and 20 relief appearances. Only Mike Minor and Lance Lynn pitched more innings for Texas.
The 28-year-old made his big league debut with a start for Seattle in 2016. He was 6-11 with a 5.64 ERA the past two seasons for Texas.