Background: Use of communication theories in the development of pictorial health warning labels (graphic warning labels) for cigarette packaging might enhance labels’ impact on motivation to quit, but research has been limited, particularly among low socioeconomic status (SES) populations in the U.S. This qualitative study explored perceptions of theory-based graphic warning labels and their role in motivation to quit among low-income smokers. Methods: A cross-sectional qualitative study was conducted with 25 low-income adult smokers in Baltimore, Maryland, who were purposively sampled from a community-based source population. Semi-structured, in-depth interviews were conducted from January to February 2014. Participants were asked about the motivational impact of 12 labels falling into four content categories: negative depictions of the health effects of smoking to smokers and others, and positive depictions of the benefits of quitting to smokers and others. Data were coded using a combined inductive/deductive approach and analyzed thematically through framework analysis. Results: Labels depicting negative health effects to smokers were identified as most motivational, followed by labels depicting negative health effects to others. Reasons included perceived severity of and susceptibility to the effects, negative emotional reactions (such as fear), and concern for children. Labels about the benefits of quitting were described as motivational because of their hopefulness, characters as role models, and desire to improve family health. Reasons why labels were described as not motivational included lack of impact on perceived severity/susceptibility, low credibility, and fatalistic attitudes regarding the inevitability of disease. Conclusions: Labels designed to increase risk perceptions from smoking might be significant sources of motivation for low SES smokers. Findings suggest innovative theory-driven approaches for the design of labels, such as using former smokers as role models, contrasting healthy and unhealthy characters, and socially-oriented labels, might motivate low SES smokers to quit.