Smoking rates are alarmingly high among young people experiencing homelessness (YEH), yet there are no evidence-based cessation programs for this population. This paper presents results from a pilot evaluation of a text messaging-based smoking cessation treatment, as an adjunct to brief group cessation counseling, to improve abstinence rates among 18-25-year-old smokers experiencing homelessness. The goal of this study was to estimate effect sizes for a larger trial and it was not powered to detect group differences. YEH smokers who had a working cell phone with them at recruitment were randomized to receive a group counseling session, nicotine patches, and written material on quitting (n = 37) or a similar program that also included a 6-week automated text messaging intervention (TMI) to provide ongoing support for quitting (n = 40). Smoking outcomes were evaluated through a 90-day follow-up. Seven-day point prevalence abstinence at 90-day follow-up was higher in the TMI condition than standard condition (17.50% vs. 8.11%, respectively; Cohen's h = .37); however, the 90-day continuous abstinence rate was not statistically different from zero in either condition. Reductions in the number of days smoked in the past 30 days from baseline to follow-up were greater in the TMI condition than the standard condition (-14.24 vs. -8.62, respectively; Cohen's d = .49). Adding a 6-week TMI support to a brief group counseling and pharmacotherapy protocol holds promise for smoking reduction and abstinence among YEH smokers. Results indicate that further development and evaluation of the TMI in this population is warranted. ClinicalTrials.gov Identifier NCT03874585. Registered March 14, 2019, https://clinicaltrials.gov/ct2/show/record/NCT03874585. This is the first study to evaluate the feasibility of using a text messaging-based intervention (TMI) for behavior change with 18-25 year olds experiencing homelessness, and more specifically, the first to test a TMI to provide ongoing support for smoking cessation. Small to medium effect sizes for the TMI are promising in terms of implementing a TMI using participants' own cell phones, as well as the efficacy of this approach as an adjunct to standard care (brief group counseling and pharmacotherapy) for smoking cessation among YEH.