Plasek agreed to a one-year contract with HC Olomouc of the Czech Extraliga on Sunday.
Plasek was placed on unconditional waivers by the Penguins on Wednesday in order to terminate his contract, Elliotte Friedman of Sportsnet reports.
Plasek was traded to Pittsburgh on Tuesday, along with Jack Rathbone, from the Canucks in a swap for Mark Friedman and Ty Glover.
Plasek was cut from the Canucks' training camp and assigned to AHL Abbotsford on Tuesday, per CapFriendly.
Plasek was loaned to Olomouc in the Czech Extraliga by the Canucks.
Plasek (undisclosed) was activated from injured reserve and assigned to AHL Abbotsford on Thursday, per CapFriendly.
Plasek (undisclosed) was placed on non-roster injured reserve Monday, per CapFriendly.
Plasek signed a three-year, entry-level contract with the Canucks on Tuesday.