Nearly all college student smokers also drink alcohol, and smoking and heavy episodic drinking (HED) commonly co-occur. However, few studies have examined the factors that concurrently influence smoking and HED among college students and, to date, no interventions have been developed that target both HED and smoking in this population. The objective of the current study was to develop and evaluate a mobile feedback intervention that targets HED and smoking. Participants (N = 94) were non-treatment-seeking college students (M(age) = 20.5 years, SD = 1.7) who engaged in at least a single HED episode in the past 2 weeks and reported concurrent smoking and drinking at least once a week. Participants were randomized to receive either the mobile intervention for 14 days, complete mobile assessments (without intervention) for 14 days, or complete minimal assessments (without intervention or mobile assessments). At a 1-month follow-up, compared with the minimal assessment condition, we observed significant reductions in the number of cigarettes per smoking day in both the mobile intervention (d = 0.55) and mobile assessment (d = 0.45) conditions. Among those randomized to the mobile intervention, receiving more modules of the intervention was significantly associated with a lower likelihood of any drinking during the 14-day assessment period and significant reductions in smoking at 1-month follow-up. The mobile intervention did not result in significant reductions in HED or concurrent smoking and drinking. Future research should continue to examine ways of using technology and the real-time environment to improve interventions for HED and smoking.