During the COVID-19 pandemic, specialty alcohol treatment transitioned rapidly to telehealth, which may have created barriers for some patients but increased access for others. This study evaluated the impact of the COVID-19 pandemic on alcohol treatment utilization and potential disparities. We analyzed electronic health record and claims data from Kaiser Permanente Northern California for adults with alcohol use problems (alcohol use disorder or unhealthy alcohol use diagnoses) during pre-COVID-19 (March to December 2019, n = 32,806) and COVID-19 onset (March to December 2020, n = 26,763). Generalized estimating equation models were fit to examine pre-COVID-19 to COVID-19 onset changes in alcohol treatment initiation, engagement, and retention (days in treatment). Heterogeneity in pre-COVID-19 to COVID-19 onset changes in treatment utilization by age, race, and ethnicity; neighborhood deprivation index (NDI); and comorbid medical and psychiatric disorders were also examined. Treatment initiation increased during the COVID-19 onset period (adjusted odds ratio [aOR] = 1.46; 95% CI = 1.41-1.52). The increases in odds of treatment initiation during the COVID-19 onset period compared with the pre-COVID period were largest among patients aged 18-34 years (aOR = 1.59; 95% CI = 1.48-1.71), those without medical conditions (aOR = 1.56; 95% CI = 1.49-1.65), and those without psychiatric disorders (aOR = 1.60; 95% CI = 1.51-1.69). Patients aged 18-34 years (aOR = 5.21; 95% CI = 4.67-5.81), those with the second highest NDIs (aOR = 4.63; 95% CI = 4.12-5.19), and those without medical (aOR = 4.34; 95% CI = 4.06-4.65) or psychiatric comorbidities (aOR = 4.48; 95% CI = 4.11-4.89) had the greatest increases in telehealth treatment initiation from pre-COVID-19 to COVID-19 onset. Treatment engagement and retention also increased during COVID-19 onset, with the greatest increase among patients aged 35-49 years who initiated treatment via telehealth (engagement: aOR = 2.33; 95% CI = 1.91-2.83; retention: adjusted mean difference [aMD] = 3.3 days; 95% CI = 2.6-4.1). We found no significant variation of changes in treatment utilization by race and ethnicity. The transition to telehealth in this healthcare system may have attracted subgroups of individuals who have historically underutilized care for alcohol use problems, particularly younger and healthier adults, without exacerbating pre-pandemic racial and ethnic disparities in treatment utilization.