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The Fox medical drama, which stars Hugh Laurie, will conclude on May 21 after eight seasons.
Morrison, who played Dr Allison Cameron from 2004 to 2010, told Entertainment Weekly: "No-one's contacted me [about returning], and we're way too close for it to even be a possibility."
The actress, who currently stars in ABC's Once Upon a Time, added: "It's a really special show and became an important part of television pop culture. I feel really lucky to have been a part of it."
Last year, Morrison told Digital Spy that she would "love" to return to House for a guest appearance.
"I love Cameron and I'll always have an affection for [that character]," she said. "So if I were given the opportunity to [come back], of course I would."
Lisa Edelstein (Lisa Cuddy) will also be absent from the final House episode, it was confirmed last month.
The instalment will be directed and co-written by House creator David Shore.
> House: Saying goodbye to Hugh Laurie's medical maverick
Watch Jennifer Morrison discuss a possible House return with Digital Spy in 2011 below:
