Wilson was activated by the Pirates on Saturday, Alex Stumpf of DKPittsburghSports.com reports.
Wilson was dealt from Atlanta to Pittsburgh on Friday as part of the package for Richard Rodriguez, and he'll claim a major-league roster spot. The 23-year-old served as a starter in each of his eight big-league appearances with Atlanta this year and posted a 5.88 ERA and 1.69 WHIP in 33.2 innings. The Pirates haven't specified how they'll use Wilson, but he could be utilized as a long reliever for now.