Tobacco use among cancer patients is associated with an increased mortality and poorer outcomes, yet two-thirds of patients continue using following diagnosis, with disproportionately higher use among racial/ethnic minority and low socioeconomic status patients. Tobacco treatment services that are effectively tailored and adapted to population characteristics and multilevel context specific to settings serving diverse patients are needed to improve tobacco cessation among cancer patients. We examined tobacco use screening and implementation needs for tobacco treatment services to inform equitable and accessible delivery within a large comprehensive cancer center in the greater Los Angeles region. We conducted a multi-modal, mixed methods assessment using electronic medical records (EMR), and clinic stakeholder surveys and interviews (guided by the Consolidated Framework for Implementation Research). Approximately 45% of patients (n = 11,827 of 26,030 total) had missing tobacco use history in their EMR. Several demographic characteristics (gender, age, race/ethnicity, insurance) were associated with greater missing data prevalence. In surveys (n = 32), clinic stakeholders endorsed tobacco screening and cessation services, but indicated necessary improvements for screening/referral procedures. During interviews (n = 13), providers/staff reported tobacco screening was important, but level of priority differed as well as how often and who should screen. Several barriers were noted, including patients’ language/cultural barriers, limited time during visits, lack of smoking cessation training, and insurance coverage. While stakeholders indicated high interest in tobacco use assessment and cessation services, EMR and interview data revealed opportunities to improve tobacco use screening across patient groups. Implementing sustainable system-level tobacco cessation programs at institutions requires leadership support, staff training, on routine screening, and intervention and referral strategies that meet patients’ linguistic/cultural needs.