This study aims to analyze the relationship between social isolation and loneliness with smoking in older adults. This is a cross-sectional, population-based study performed with 986 individuals aged 60 years or older. Data were collected from the Health Survey of the Municipality of Campinas (ISACamp 2014/2015), state of São Paulo, Brazil. We estimated the prevalence of smoking and smoking cessation according to independent variables and tested the associations using the chi-square test, considering a 5% significance level. Adjusted prevalence ratios were calculated using simple and multiple Poisson regression. Smoking and smoking cessation were not associated with most variables that indicate objective social isolation. "Often or always" loneliness was related to a higher prevalence of smoking (PR = 2.25; 95%CI: 1.38-3.66) whereas loneliness accompanied of self-reported emotional problems or common mental disorders was strongly associated with smoking and with lower smoking cessation (PR = 6.24; 95%CI: 1.37-28.47 and PR = 0.46; 95%CI: 0.28-0.77, respectively). These findings indicate that loneliness is a psychosocial aspect related to tobacco use which hinders smoking cessation in older adults, emphasizing the importance of emotional problems in this association.