Advance care planning is relevant for homeless individuals because they experience high rates of morbidity and mortality. The impact of advance directive interventions on hospital care of homeless individuals has not been studied. The objective of this study was to determine if homeless individuals who complete an advance directive through a shelter-based intervention are more likely to have information from their advance directive documented and used during subsequent hospitalizations. The advance directive included preferences for life-sustaining treatments, resuscitation, and substitute decision maker(s). A total of 205 homeless men from a homeless shelter for men in Toronto, Canada, were enrolled in the study and offered an opportunity to complete an advance directive with the guidance of a trained counselor from April to June 2013. One hundred and three participants chose to complete an advance directive, and 102 participants chose to not complete an advance directive. Participants were provided copies of their advance directives. In addition, advance directives were electronically stored, and hospitals within a 1.0-mile radius of the shelter were provided access to the database. A prospective cohort study was performed using chart reviews to ascertain the documentation, availability, and use of advance directives, end-of-life care preferences, and medical treatments during hospitalizations over a 1-year follow-up period (April 2013 to June 2014) after the shelter-based advance directive intervention. Chart reviewers were blinded as to whether participants had completed an advance directive. The primary outcome was documentation or use of an advance directive during any hospitalization. The secondary outcome was documentation of end-of-life care preferences, without reference to an advance directive, during any hospitalization. After unblinding, charts were studied to determine whether advance directives were available, hospital care was consistent with patient preferences as documented in advance directives, and hospital resource utilization during admission. During the 1-year follow-up period, 38 participants who completed an advance directive and 37 participants who did not complete an advance directive had at least one hospitalization (36.9 vs. 36.2 %, p = 0.93). Participants who completed an advance directive were significantly more likely to have documentation or use of an advance directive in hospital, compared to participants who did not complete an advance directive (9.7 vs. 2.9 %, p = 0.047). Without reference to an advance directive, documentation of end-of-life care preferences occurred in 30.1 vs. 30.4 % of participants, respectively (p = 0.96), most often due to documentation of code status. There were no significant differences in resource utilization between admitted patients who completed and did not complete an advance directive. In conclusion, homeless men who complete an advance directive through a shelter-based intervention are more likely to have their detailed care preferences documented or used during subsequent hospitalizations.