The actress will reprise her role of Chloe O'Brian in new limited series 24: Live Another Day, Fox announced at the Television Critics Association press tour.
The 12-part drama - which also sees Kiefer Sutherland back as 24 lead Jack Bauer - is expected to premiere in April 2014, showrunner Howard Gordon recently revealed.
"I am thrilled to be working with Howard and the writers again - and of course, Kiefer," Rajskub said in a statement. "I'm going to start sharpening my computer skills now!"
Rajskub debuted as CTU analyst Chloe in 24's third season and remained with the series until its final regular run in 2010, with her character becoming a fan favourite.
The 42-year-old previously admitted that she had "high hopes" of returning to the part. Beyond Rajskub and Sutherland, no further casting has been announced for Live Another Day.
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