Wagner played hunky cop-turned-spy Frisco Jones in the 1980s and '90s, but hasn't appeared on the soap since 1995.
TVGuide.com said he is among the many daytime-drama icons returning to "GH" this year for the ABC show's 50th anniversary.
No details about his plot line or when he will show up in fictional Port Charles were reported.
Since leaving "GH," Wagner has starred in "The Bold and the Beautiful," "Melrose Place," "Sunset Beach" and "Santa Barbara," and competed on "Dancing with the Stars."
Sean Kanan, Finola Hughes, Robin Mattson, Ian Buchanan, Tristan Rogers and Lynn Herring have all recently returned to "General Hospital," while Genie Francis and Kin Shriner are expected back next month.