At the end of his life, Haim shared a month-to-month rental at the Oakwood Apartments between Burbank and the Hollywood Hills with his mother, who has breast cancer. Haim did not own a car. Christopher Ameruoso, Haim's neighbor for a year, said Haim sometimes could be seen wandering around the complex, "looking for companionship, looking for friends."
On March 10, 2010, after a 9-1-1 call from his mother, Haim was taken from their home by paramedics to Providence Saint Joseph Medical Center in Burbank, and pronounced dead at 2:15 a.m. (10:15 UTC). Los Angeles police stated that his death appeared to be an accidental overdose and that four bottles containing Valium, Vicodin, Soma (a muscle relaxant) and Haloperidol (an anti-psychotic) were retrieved, later confirmed as prescribed by a specialist, but that no illegal drugs were found at the scene. It emerged that Haim had used aliases to procure 553 prescription pills in the 32 days prior to his death, "doctor-shopping" seven different doctors and using seven pharmacies to obtain the supply, which included 195 Valium, 149 Vicodin, 194 Soma and 15 Xanax.
Haim had been ill with flu-like symptoms for two days before his death. A doctor called on him and took his temperature, but did not suspect serious problems. At one stage, Haim woke his mother and said, "Mom, can you please come and lie next to me, I'm not feeling very good." After he attempted to walk around shortly after midnight, she saw him collapse. Assistant Chief Coroner Ed Winter said: "As he got out of bed he felt a little weak and went down to the floor on his knees." Prior to the official autopsy reports being made available publicly, Haim's mother stated that the coroner had given her a "courtesy call" to state his preliminary findings that Haim died of pulmonary edema and was suffering from an enlarged heart and water in the lungs. Haim's agent discounted the possibility of an overdose, citing his recent drive toward clean living and affirming that he had been completely drug-free for two weeks. Haim's primary doctor confirmed to Bureau of Narcotics Enforcement investigators that Haim was addicted to pain medication.