The actress made her debut last week in the Season 11 premiere as Jenny, Charlie Harper's (Charlie Sheen) long-lost illegitimate 25-year-old daughter who likes everything her dad liked, including women.
Tamblyn originally signed on for only five episodes. The move comes as she's working on the fifth and last episode of her original arc.
The character, who will appear in five of the first six episodes of the CBS sitcom's latest season, was introduced in the season opener when she shocked her uncle Alan (Jon Cryer) by showing up at Walden’s (Ashton Kutcher) beach house trying to connect with what’s left of her family while also pursuing an acting career.
Tamblyn, 30, fills the void left by "half man" Angus T. Jones, who departed the show as a regular after the last season. His role as Alan's son Jake has been reduced to recurring status while the 19-year-old actor attends college.
While she received mostly positive reviews for her portrayal of Jenny, Tamblyn's debut failed to boost the show's ratings like Kutcher's addition did two years ago, falling 17% from last season's premiere to 11.5 million viewers and a 2.9 demo rating without "Big Bang Theory" as its lead-in.
The actress previously starred in a CBS series as the lead on "Joan of Arcadia," which debuted exactly a decade ago. Her other TV credits include "General Hospital," "House" and "The Increasingly Poor Decisions of Todd Margaret," which starred her husband David Cross ("Arrested Development").
"Two and a Half Men" Season 11 continues Thursdays at 9:30/8:30 p.m. CT on CBS.