The deal announced by the National League East champions on Wednesday includes a 2022 team option for $1.25 million.
The 36-year-old Tomlin was 2-2 with a 4.76 ERA in 17 games with Atlanta this season. He had a 2.95 ERA in 12 relief appearance and had a 6.33 ERA in five starts.
Tomlin signed with Atlanta in 2019 following nine seasons with Cleveland. He has a 4.69 career ERA. He 1.31 walks per nine innings ranks best among all active pitchers with at least 900 innings.
Tomlin made Atlanta’s Opening Day roster this season after signing a minor league deal that included an invitation to spring training.