Background The high rates of smoking in adults with serious mental illness (SMI) increases risk for COVID-19 infection. The purpose of this paper is to present the results of a smoking cessation intervention that was adapted to be offered by phone during a Shelter in Place (SIP) period in San Francisco, California, at the beginning of the COVID-19 pandemic. Methods During the SIP, we offered counseling sessions by phone to five participants. At the end of each session, we assessed readiness to quit, tobacco cessation or reduction, and inquired about the impact of the shelter in place on smoking habits and mental health. Grounded theory guided data collection and analysis. Results The categories that emerged around barriers and facilitators for smoking cessation were COVID-19–related stressors, having purpose, structure and feelings of connections, and the importance of quitting aides for smoking cessation. Conclusion Offering telephone based smoking cessation counseling to adults with SMI while they shelter in place may improve their readiness to quit.