We present a case of a 65-year-old woman who developed a delayed deltoid compartment syndrome after resuscitation via humeral intraosseous access. Initially she was treated conservatively but then was taken emergently for a fasciotomy. After confirming the diagnosis with compartment pressures, a 2-incision approach was employed and a large hematoma was evacuated from the inferior margin of the anterior deltoid. The rest of the deltoid was inspected and debrided to healthy bleeding tissue. Her fasciotomy wounds were left open to heal on their own due to her tenuous clinical condition. At most recent follow-up, she had full range of motion in her shoulder and no residual pain. Our unique case study is the first documented incidence of upper extremity compartment syndrome after intraosseous access. Additionally, our case supports using humeral access only as a second-line option if lower extremity access is not available and prolonged vigilant monitoring after discontinuing intraosseous access to prevent disastrous late complications.