In 2016, Flynn was cast as Mike the intern in "BrainDead". Flynn recently starred in Vineyard Theatre's production of "Kid Victory", a newly-written musical about 17-year-old Luke (played by Flynn) from Kansas, who recently disappeared from his hometown and finds himself growing close with the town's oddball, Emily. Flynn has also acted in 11 plays, including "Much Ado About Nothing and The Crucible". He created a one-man show, entitled "Driving Mein Fuhrer", which he performed in a studio show for New World School of the Arts.
It was like, the hardest audition ever because it was like three lines and I was like, ‘I don’t even know who this person is’. (...) He’s a kid who’s not from the right part of town, but is popular at school despite his interesting home life. For some reason that really attracted me, because I remember being in high school and you wear all these masks. Justin wears masks constantly. It’s almost like a survival technique because you see what happens to him at home and you see… being a product of how you’re brought up and how that can make you interact with other human beings.
— Brandon about auditioning for the role of Justin
My favorite part of this whole season, selfishly, is the relationship that starts to form between Clay and Justin. And the whole Jensen family, and the way that they embrace Justin. They were just like the best thing ever, because it was just like, you know, more than just a one-off scene about, like, my heroin addiction. It was, like, just a little slice of life. Which I never thought would be, like, my cup of tea. You know, I'm usually the one who's like "Lets get real sad and tragic!". But it was really awesome to just sit at a breakfast table and have, like, these awkward moments. And just have, like, this-- this levity, which I think is gonna be so enjoyable for the audience as well.
— on his character being taken in by the Jensens and his relationship with Clay.[src]
I think it's so important how survivors choose to stand up, when they choose to stand up, and it's so interesting to have those two different kinds of boys in these two different kinds of pockets of, you know, of the high school jungle, have that shared experience.
— Brandon Flynn about Tyler and Justin's experience with sexual assault[src]
His story is so much so of how so many young people’s lives could end up. His self-destructive behavior, reliance on substance, the lack of tools to deal with not only his addiction, but what’s underneath all that. We never see Justin at rehab, but in the fourth season, he comes back from rehab and we see that. We see a guy who’s found an easier, softer way, until he’s not, until he’s the same scared boy we’ve come to know and love. You know, so much of Justin was struggle. Justin didn’t know he was sick at that point. He knew something was up, and we’re watching this really scared guy go to prom and he’s seeing what his life can be, which is full of people who love him. That is why is it just so damn sad when you watch him fall. I think the hardest part for Justin in that is, one, his body is just shutting down, and through a disease that has this ethos of shame behind it. As the guy who played him, who, for like eight months out of the year, stepped into his worn-out and tired shoes, emotionally, yeah, you know, it’s a heart breaker. I want people to believe that Justin’s story is not necessarily always the outcome, that there’s duality to life. There’s addiction and there’s recovery, there’s lost and there is found, there is light in the darkness.