She will be playing Madeline Reeves, the mother of Nina Clay and Nathan West (aka James Reeves).
Mills will debut on the March 14 episode.
This marks a return to daytime for Mills who started her television career on THE SECRET STORM before starring as Laura Donnelly in the original cast of LOVE IS A MANY SPLENDORED THING. Mills played the sister of longtime GH star Leslie Charleson on LIAMST.
Mills other primetime soap roles include Sherry Doucette on MELROSE PLACE and Bitsy Lourd in GCB.