The ESPN sportscaster and celebrated Paralympian swimmer took to the stage with Val Chmerkovskiy to perform a cha cha set to "Born Ready" by The Disco Fries, and the pair delivered one of the night's most impressive performances.
However, before they stepped out, Arlen's emotional story was shared in a pre-taped package, and it became clear that her journey to dancing on the show was more incredible than you could have guessed.
When Arlen was 11, she developed two debilitating afflictions that caused inflammation of her spinal cord and prevented her from moving, talking or even eating. She later fell into a vegetative state for four years, and doctors did not have high hopes for her recovery.
When she turned 15, she began to emerge from her vegetative state, and even started to regain some of her motor functions.
As her recovery progressed, she began to relearn how to walk -- a skill she didn't even begin to develop until a year and a half ago, after spending a decade in a wheelchair. Even now, she still can't feel her legs.
"I think this is a really big statement to myself, as well as to the people who wrote me off, that I'm here! I lived! And I'm ready to dance," Arlen said.
"I've seen some incredible routines on this show, but that was one of the most joyous performances I've ever seen," judge Carrie Ann Inaba gushed. "There's something spectacular about you."
In the end, the pair earned a total score of 19 out of 30, putting them in 5th place out of 12 couples.
Dancing With the Stars returns next Monday at 8 p.m. ET/PT on ABC.