People living with mental illnesses (MI) have a specific need that requires tailored tobacco treatment (TT) information to be delivered in a desirable, appropriate, and acceptable manner to increase their receptivity. In this mixed-method study, we aimed to develop tailored TT pamphlets for people with MI. In Phase I, we explored perspectives on tailored TT information from mental health providers (MHPs) and individuals with MI. In Phase II, we assessed the desirability, applicability, and acceptability of the developed tailored TT pamphlets. Semistructured interviews were used to obtain qualitative and quantitative data from 16 MHPs and 13 individuals with MIs recruited from an inpatient psychiatric facility. Thematic analysis and descriptive statistics were used to synthesize the data. The study guides the development of effective approaches, presentations, and content to enhance TT engagement for people with MI. The proposed tailored TT pamphlets proved desirable, applicable, and acceptable for individuals with MI. We recommend developing tailored TT information for people with MI in collaboration with MHPs and the target audience. Clear, concise communication is crucial, ensuring desirability, applicability, and acceptability. Further research should identify effective approaches and evaluate tailored TT materials to enhance program effectiveness.