The Stargate SG-1 actress will appear in the cult drama's eighth season as an angel named Naomi, according to TVLine.
Showrunner Jeremy Carver described the character as "cool and mysterious" and "part of a new group of angels we've never seen before".
Tapping will make her debut in the season's seventh episode, titled 'A Little Slice of Kevin'. The 47-year-old English-born Canadian star played Samantha Carter on Stargate SG-1 and reprised her role in various spinoffs.
She also starred in recently-axed Syfy series Sanctuary and has appeared in episodes of The X Files and Due South.
Veteran actor Mike Farrell - best known for his role on the television version of M*A*S*H - has also been cast on Supernatural. The 73-year-old will play a "mentalist with a slippery grasp on reality" in the new run's eighth episode.
Supernatural returns to The CW on Wednesday, October 3 at 9/8c and airs on Sky Living in the UK.
> Supernatural: The fall (and rise?) of The CW's cult drama
Watch a promo for the return of Supernatural below: