Emmy Rossum poses at an event for the television series "Shameless" in Los Angeles. Picture: Reuters

Emmy Rossum penned an emotional post on Thursday, announcing that she will be saying goodbye to “Shameless” after the show’s upcoming ninth season.

Taking to Facebook, Rossum wrote: "Until 'Shameless' came into my life 8 years ago, I led that kind of transient wonderful life of an actor. And I never realized how much I actually craved the kind of continuity that this show has given me.

"See, in real life, unlike Fiona, I'm an only child. I never had a big family. Being ensconced in that messy Gallagher family love is something I'd always dreamed of."

"The opportunity to play Fiona has been a gift."

Rossum has played Fiona Gallagher on the Showtime series since 2011. She co-stars on the show with on-screen patriarch William H. Macy.

Showtime Networks programming chief Gary Levine said the network was saddened by Rossum’s decision to leave and praised her work as Fiona, daughter to William H. Macy’s dysfunctional patriarch, Frank.

Executive producer John Wells said work is underway on a season finale aimed at giving Rossum and her character a worthy send-off.

The ninth season of “Shameless” debuts on 9 September.

Read Rossum's full post below.