The actress will play a love interest for Tom (Doug Savant) when she joins the show, TV Line reports.
The role was originally expected to go to former Friends star Jessica Hecht, but sources have claimed that the negotiations were unsuccessful.
Reports that Tom would be getting a new love interest began circulating earlier this month, when executive producer Bob Daily hinted that Lynette (Felicity Huffman) will also be with someone new.
Parker recently appeared in Pretty Little Liars and has previously worked on shows including ER, JAG and Less Than Perfect.
The eighth and final season of Desperate Housewives will premiere on September 25 on ABC.
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