It was first reported that the Body of Proof actress would reprise her role as Katherine Mayfair in November last year.
The character last appeared towards the end of the ABC drama's sixth season, in the 2010 episode 'My Two Young Men'. She will make a one-off reappearance in the final episode, reports TVLine.
The installment will be written by series creator Marc Cherry and is scheduled to air on May 13.
Felicity Huffman (Lynette Scavo) previously admitted that she is "dreadfully" scared about Desperate Housewives coming to an end.
"People so identify you with the part you've been playing," the actress explained in January. "It's hard to find work for a long time [once a popular series ends]."
Desperate Housewives returns to ABC on April 29.
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Watch a promo for the next Desperate Housewives below: