Monaghan will make his final appearance as Ian Gallagher in season nine's sixth episode, titled "Face It, You're Gorgeous."
In the two photos with Monaghan, he is joined by Ethan Cutlosky, who plays Carl Gallagher, and Jeremy Allen White, who plays Lip Gallager.
The actor also shared another photo, showing White with Christian Isaiah as Liam Gallagher, Shanola Hampton as V and Steve Howey as Kev.
"I have been a series regular on this show for roughly ten years," Monaghan, 25, wrote on his Instagram page. "I was the tender age of 15 when we shot the pilot, and I came of age in so many ways, both legally and personally. I was very lucky to mature and grow with this show. Experiencing so many firsts, maturing as an actor, a professional, and a human. In the process gaining friends, family, and the best coworkers a very lucky actor could ask for, and for this I can be nothing but gracious."
Monaghan also said he knew this weekend's episode would be his last since last year, but did not want to announce it until now to kept it a surprise as long as he could.
"This role has been a joy to inhabit, a wild and special ride, and I’d like to thank Shameless as well as you, the viewers, for being there with him," Monaghan wrote. "Goodbye, Ian Clayton Gallagher. We’ll meet again?"
Monaghan is the second major Shameless actor to leave the series, following Emmy Rossum, who said season nine will be her last in August. However, it could also be one of the last seasons for Gallagher family patriarch Frank, played by William H. Macy.
"I know there's another 10 years of stories, and I'd love to see them. But when I think about acting them [out], my back starts to hurt a little bit," Macy told The Hollywood Reporter in September. "I know I want to do another season or two, and after that we shall see."
Macy also said the series will be "empty-nesting a bit" without Rossum. "I hoped that she would stay, but you get close to year 10 and start thinking about life post-Shameless. It's horrifying and exciting," the Oscar-nominated actor said.
Like Monaghan, Rossum also pointed out how important her on-set family became in her life.
"We have made over 100 hours of television. That’s no small feat," Rossum wrote on Facebook. "There’s a new study that says it takes 100 hours to become friends with someone. The Gallaghers have been in people's living rooms for 100 hours. So, it makes sense. We can feel your connection to us, to these characters. In the airport, in restaurants, on the street, when people call out 'Hi Fiona' 'Oh my god, it’s Lip' or 'Screw you Frank!'... it feels good."0comments
New episodes of Shameless air on Showtime Sundays at 9 p.m. ET.
Photo Credit: Showtime