Ryan grew up in Corryton, Tennessee, exploring the hills of East Tennessee with his older brother and friends. He nurtured an early passion for service through the JROTC program at Gibbs High School. A history buff, he had long known he wanted to serve his country.

After graduating in 2016, he enlisted in the Army as an infantryman and qualified as a paratrooper with the 82nd Airborne Division. He began his career as a scout and deployed to Afghanistan as a gunner from 2017 to 2018. In 2020, drawn by an interest in psychology, he joined the 9th Psychological Operations Battalion (Airborne) at Fort Bragg, where he served as a psychological operations noncommissioned officer. In 2021, he returned to Afghanistan with the 9th to help evacuate American civilians and Afghan refugees. On August 26, 2021, he was one of thirteen service members killed when a suicide bomber detonated an improvised explosive device at Hamid Karzai International Airport.

His legacy lives on through his family, friends, and fellow soldiers, as well as through the Respect and Remember Foundation, a nonprofit established by his family in his honor. The foundation provides scholarships to JROTC and ROTC cadets and support for military families. In tribute to his service and sacrifice, the post office at 9355 113th Street in Seminole, Florida, was named the Army SSG Ryan Christian Knauss Memorial Post Office Building.