Wren made the announcement about two hours before the deadline for clubs to add players they would like to include on their postseason roster. Earlier in the day, Wren satisfied his wish to add a right-handed bat by acquiring Matt Diaz from the Pirates, also for a player to be named.
"Jack is an exceptional middle infielder, and we're really excited to get him," Wren said. "He's hitting close to .250 for the season, but he's been much better recently and playing like he is capable of playing. We're thinking he is a guy who will add to our club like Matt Diaz did. These are the kind of guys we think are winners."
Wilson may not be the top-notch defensive shortstop he was during the early years of his career with the Pirates, but he's still an above-average defender who hit .249 with a .283 on-base percentage in 62 games for the Mariners this year.
The 33-year-old Wilson, on the disabled list with a bruised left heel, will be eligible to be activated on Saturday.
With Wilson's acquisition, the Braves have gained a better middle-infield option than they had in Julio Lugo, who has batted .136 in 22 games.
Mark Bowman is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.