It has been a big celebration day for every avid watcher of "Grey's Anatomy" as Kate Walsh, who played Dr. Addison Montgomery, will return to the show!

Walsh, who debuted as Addison in the show's Season 1 finale in 2005 and later became a part of the spinoff "Private Practice," surprised the fans as she will come back to the show for a multi-episode arc on their 18th season, per Fox News.

The source was able to confirm from ABC representatives regarding her appearance. However, they were not able to give more details regarding her storyline. The actress also shared numerous promotional videos on Twitter and Instagram as she is excited about her return.

Dr. Addison Is Back

Addison went from a recurring character to a series regular. And by the third season of "Grey's Anatomy," the show's creator, Shonda Rhimes, sent Addison to Los Angeles, as the actress starred on "Private Practice."

Deadline described Walsh's character, Addison Forbes Montgomery, as a world-class gynecological and neonatal surgeon. Her character is married to Derek Shepherd, played by Patrick Dempsey, and has a history with Meredith Grey, the lead character played by Ellen Pompeo.

ABC's No. 1 drama series will have its return on September 30, at 9 pm. The show dropped several main characters from its last season, including Giacomo Gianniotti and Jesse Williams leaving.

READ ALSO: Ellen Pompeo Drops Acting After 'Grey's Anatomy,' Was It Because of Tension With Co-Stars?-Real Reason Revealed

Sources say that Meredith's scenes mostly took place on a beach as she hovered between life and death due to COVID-19, allowed several dead characters for the past season. The show also made Patrick Dempsey, T.R. Knight, and Chyler Leigh featured on the show.

For the upcoming season, ABC also confirmed that Kate Burton, Meredith's mother, will be featured in multiple episodes and Peter Gallagher.

Other projects that Walsh participated in include "The Handler" in Netflix's 2019 series "The Umbrella Academy," she also appeared in "Emily in Paris," and "Honest Thief" with Liam Neeson. She also made appearances in "Sometime Other Than Now" and Amazon's sci-fi flick, "3022."

READ MORE: How 'Modern Family' Star Eric Stonestreet Proposed to GF Lindsay Schweitzer is Quite Funny [DETAILS]