Aho was placed on waivers Sunday, per Elliotte Friedman of Sportsnet.
Aho agreed to terms on a two-year, $1.55 million contract with Pittsburgh on Tuesday.
Aho will play Wednesday versus the Penguins, Stefen Rosner of NHL.com reports.
Aho will be rested for Wednesday's matchup with Pittsburgh, Andrew Gross of Newsday reports.
Aho (upper body) was taken off the injured reserve list Wednesday, per the NHL media site, which indicates he'll play in the evening's game against Boston.
Aho (upper body) is expected to be a game-time decision for Wednesday's contest versus Boston, coach Lane Lambert told Andrew Gross of Newsday.
Aho (upper body) is skating with the team but won't be ready to face San Jose on Tuesday.
Aho (upper body) was placed on injured reserve Monday.
Aho (upper body) won't play Saturday against Philadelphia, according to Andrew Gross of Newsday.
Aho (upper body) was injured in Friday's 5-3 win over Ottawa, per Callum Fraser of NHL.com.