Medical hospitalizations are relatively common among individuals who have substance use disorders (SUDs) and represent opportunities for patient engagement and treatment. Posthospitalization transitions of care are an important element of providing full-spectrum inpatient SUD care; however, little is known about clinicians' experiences with postdischarge care transitions. We conducted a cross-sectional study surveying hospital-based medical clinicians (ie, "hospitalists") across 2 large health systems in the state of Utah to assess current practices, barriers, facilitators, and perceptions toward posthospitalization care transitions for patients with SUDs. We used Wilcoxon signed-rank tests to identify the most impactful barriers and facilitators among all respondents. We used logistic regression models to explore the influence of hospitalists' attitudes toward providing SUD care on perceived barriers and facilitators. The survey was distributed to 429 individuals across 15 hospitals. Eighty-two hospitalists responded to the survey (response rate, 21.4%). Most respondents frequently cared for hospitalized patients with SUDs (n = 63, 77%) and prescribed medications for SUDs (n = 44, 56%). Four respondents (5%) felt that patients received adequate support during care transitions. Lack of social support ( P < 0.001) and social factors such as lack of transportation ( P < 0.001) were perceived as the largest barriers to successful care transitions. Conversely, a partnering outpatient clinic/clinician ( P < 0.001) and outpatient-based care coordination ( P < 0.001) were perceived as the strongest facilitators. Respondents' attitudes toward people with SUDs had a modest effect on perceived barriers and facilitators. Hospitalists perceived increased outpatient SUD treatment infrastructure and transitional care supports as most important in facilitating posthospitalization care transitions for patients with SUDs.