The actor will play a recurring role on season two of sophomore dram "The Catch", which is produced by Shonda Rhimes, according to The Hollywood Reporter.
Details on Knight's role are being kept under wraps but Rhimes welcomed Knight.
"This has been a thrilling secret to keep! One of my favorite family members is home!," she said.
Knight's casting reunites him with Rhimes and her Shondaland partner Betsy Beers as well as "The Catch" showrunner Allan Heinberg.
"Working with Shonda, Betsy and Allan again fills me with immense joy. I am heartened to be returning to Shondaland and excited to work with this exceptional cast!," Knight said.
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Knight's character George was killed off in "Grey's Anatomy" amid some drama.
The actor, who made the decision to come out, clashed with former "Grey's Anatomy" co-star Isaiah Washington and asked to be released a year early from his contract after what he called a "breakdown in communication" with Rhimes and a lack of screen time.
George's death still ranks as one of the most shocking deaths on Grey, which is known for killing off its popular characters in dramatic ways.