Aho agreed to terms on a two-year, $1.55 million contract with Pittsburgh on Tuesday.
Aho managed just nine points in 58 regular-season games for the Islanders last season while averaging 16:23 of ice time. The 28-year-old Swede joins fellow free-agent acquisition Matt Grzelcyk on a revamped Penguins blue line, though a spot in the lineup is not guaranteed for Aho. He'll enter training camp in a positional battle with the likes of Jack St. Ivany and John Ludvig (wrist).