Boles, who has appeared in eight games in his Cardinal career, will be a graduate transfer. He announced he will depart after he graduates at the end of Stanford's winter quarter.
"First and foremost, I am grateful for the phenomenal academic and athletic opportunities that were provided to me through Stanford University," Boles said in a statement posted on Twitter. "Coach [David] Shaw and his staff have been great mentor for me during my 4 years in the Cardinal Football program. I have matured tremendously as a player and a man as a result. Furthermore, the brotherhood I have gained through my teammates at Stanford will last forever, it is a lifetime bond I'm so fortunate to have. I have love for each and every one of you.
"While very appreciative of my career at Stanford, I am excited for my future as I am officially entered in the transfer portal and ready for my next opportunity after graduation at the conclusion of the winter quarter."
Over the summer, Boles was involved in both the Pac-12 unity group -- which has fought for health and safety protections, compensation and racial justice from the conference -- and the #WeWantToPlay movement, which involved players from across the country and pushed for similar measures.
Boles was one of the players who organized a video conference that included a dozen players -- including Clemson's Trevor Lawrence, Ohio State's Justin Fields, Oregon's Penei Sewell and Oklahoma State's Chuba Hubbard -- in an effort to save the fall college football season safely for players while also advocating for a player's union.