The Reds demoted reliever Barrett Astin to Triple-A Louisville in a corresponding move, reducing the team's bullpen to seven pitchers.
Mesoraco, who as an All-Star in 2014 when he hit .273 with 25 home runs and 80 RBIs, missed most of last season after having shoulder and hip surgeries.
Since his breakout 2014 season, Mesoraco has played just 39 major league games the past two seasons. He finished a 20-day rehab assignment on Tuesday.
If the Reds were to demote Turner and he went unclaimed on waivers, they would have to offer him back to the Minnesota Twins, the team from which they selected him in the Rule 5 draft. For Turner to remain in the Reds organization beyond 2017, he has to remain on the team's 25-man roster the entire season.
Reds manager Bryan Price said Wednesday that having Turner on the team allows him to use Mesoraco or Bandhart in pinch-hitting situations when they aren't starting.