Concomitant excessive alcohol consumption and benzodiazepine use is associated with adverse health outcomes. We examined associations of unhealthy alcohol use and other patient characteristics with benzodiazepine use. A cross-sectional analysis of 2,089,525 Kaiser Permanente of Northern California outpatients screened for unhealthy alcohol use in primary care between November 1, 2014, and December 31, 2016. We fit multivariable generalized linear models to estimate the associations between unhealthy alcohol use and benzodiazepine dispensation and, among patients who were dispensed a benzodiazepine, mean doses (in mean lorazepam-equivalent daily doses [LEDDs]) and prescription durations. We controlled for patient sex, age, race/ethnicity, estimated household income, Charlson Comorbidity Index (CCI) score, anxiety disorder, alcohol use disorder, insomnia, musculoskeletal pain, and epilepsy. In the 12 months centered around (6 months before and 6 months after) the first alcohol-screening visit, 7.5% of patients used benzodiazepines. The following characteristics were independently associated with higher rates of benzodiazepine use, higher LEDD, and longer prescription duration: older age, white race/ethnicity, lower estimated household income, higher CCI score, and the presence of an anxiety disorder, insomnia, musculoskeletal pain, or epilepsy. Women and patients with an alcohol use disorder or unhealthy alcohol use, compared with men and patients with low-risk drinking or abstinence, were more likely to use a benzodiazepine; however, their LEDDs were lower and their prescription durations were shorter. Benzodiazepine use in primary care was associated with older age, female sex, white race/ethnicity, lower socioeconomic status, and unhealthy alcohol use. These findings may be applied to develop policies and interventions to promote judicious benzodiazepine use.