The Pirates signed Kessinger to a minor-league contract Wednesday.
Kessinger -- who had been in the Mets organization -- will help backfill the organization's shortstop depth following the injury to Konnor Griffin (finger). The 28-year-old infielder missed the beginning of this season with a significant hamstring strain and slashed just .151/.242/.264 in 17 games with Triple-A Syracuse.