The soap actress will portray Sam's (Chord Overstreet) mother on the Fox series, according to The Hollywood Reporter.
Meanwhile, Smallville actor John Schneider will play Sam's father.
The pair will appear on the show's eighth episode and could potentially return for more episodes in the future.
Clarke has starred on a number of soaps, including Guiding Light, As the World Turns and One Life to Live.
Glee star Charice's father was recently stabbed to death during an altercation with another man in a San Pedro convenience store.
It was announced in October that Overstreet would return to the show, after leaving the series in July to pursue a career in music.
Glee airs Tuesdays at 8pm on Fox in the US and on Thursdays at 9pm on Sky1 in the UK.