The character was originally killed alongside her daughter Jo (Alona Tal) in fifth season episode 'Abandon All Hope...'.
However, in a recent post on her Twitter account, Ferris wrote: "Yes, Ellen is back."
She later added: "Don't even think about asking for details cuz it ain't in the cards. No spoilers here. Besides, I know nothing. But should b cool, no? (sic)"
Ferris previously appeared in eight episodes of Supernatural and has also had guest roles on Human Target and V.
It is currently unknown if Alona Tal, who recently featured on CBS legal series The Defenders, will also return to the show.
Supernatural will return to The CW on January 28.