ImportanceDisparities persist across the trajectory of serious illness, including at the end of life. Patient navigation has been shown to reduce disparities and improve outcomes for underserved populations.ObjectiveTo determine the effectiveness of a lay patient navigator intervention, Apoyo con Cariño, in improving palliative care outcomes among Hispanic patients.Design, Setting, and ParticipantsThis was a multicenter randomized clinical trial that took place across academic, nonprofit, safety-net, and community health care systems in urban, rural, and mountain/frontier regions of Colorado from January 2017 to January 2021. Self-identifying Hispanic adults with serious noncancer medical illness and limited prognosis were recruited. Data were collected and analyzed from July 2022 to July 2023.InterventionsParticipants randomized to the intervention group received 5 home visits from a bilingual, bicultural lay patient navigator; participants randomized to control received care as usual. Both groups received culturally tailored educational materials. Investigators/outcome accessors remained blinded to participant assignment.Main Outcomes and MeasuresChange in score from baseline to 3 months on the Functional Assessment of Chronic Illness Therapy (FACIT) General quality of life (QOL) scale (primary outcome), Advance Care Planning (ACP) Engagement Survey, Brief Pain Inventory, Edmonton Symptom Assessment Scale, and FACIT Spiritual Well-Being subscale; at 6 months, advance directive (AD) documentation; and at 46 months or death, hospice utilization and length of stay, as well as aggressiveness of care at end of life.ResultsOf 209 patients enrolled (mean [SD] age, 63.6 [14.3] years; 108 [51.7%] male), 105 patients were randomized to control and 104 patients to the intervention. There were no statistically significant differences in the change in mean (SD) QOL score between the intervention and control groups (5.0 [16.5] vs 4.3 [15.5]; P = .75). Participants in the intervention group, compared with the control group, had statistically significant greater increases in mean (SD) ACP engagement (0.8 [1.3] vs 0.1 [1.4]; P < .001) and were more likely to have a documented AD (62 of 104 [59.6%] vs 28 of 105 [26.9%]; P < .001). There were no statistically significant differences in mean (SD) change in pain intensity score (0-10) between patients in the intervention group compared with control (−0.4 [2.6] vs −0.5 [2.8]; P = .79), nor pain interference (−0.2 [3.7] vs −0.4 [3.7]; P = .71). Patients receiving the intervention were more likely to be referred to hospice compared with patients receiving control (19 of 43 patients [44.2%] vs 7 of 33 patients [21.2%]; P = .04) and less likely to receive aggressive care at end of life (27 of 42 patients [64.3%] vs 28 of 33 patients [84.8%]; P = .046).Conclusion and RelevanceIn this randomized clinical trial, a culturally tailored patient navigator intervention did not improve QOL for patients. However, the intervention did increase ACP engagement, AD documentation, and hospice utilization in Hispanic persons with serious medical illness.Trial RegistrationClinicalTrials.gov Identifier: NCT03181750