Since 2003, Brazilian-specific legislation has stipulated that foods containing more than 1% of genetically modified (GM) ingredients must provide information regarding their origin with an identification symbol on its label. The purpose of this study was to verify the knowledge of consumers concerning the mandatory labeling of foods containing genetically modified ingredients and analyze the possible motivations behind the willingness of the consumer to buy these foods in Brazil. Research was conducted on 224 consumers of different socioeconomic levels from Limeira, São Paulo (SP), Brazil. Consumers were asked about socio-demographic variables and were assessed for their knowledge of the symbol for genetically modified ingredients on food labels. Depending on the consumers' answer about the symbol, they would be directed to a specific set of assertions. In the end, seventeen assertions were scored using a 5-point Likert scale to determine their profile. These assertions were categorized into five constructs: social trust, reduced price, perceived risk, perceived quality, and willingness to buy. This data was analyzed using Structural Equation Modelling. Most consumers (74.6%) did not recognize the symbol used in the mandatory labeling, although a younger age, a concern regarding GM foods, and a high level of education increased the chances of recognizing the symbol. Many of the consumers who were able to identify the symbol have found the GM labeling difficult to interpret. With regard to their willingness to buy GM foods, positive effects were observed for reduced price and perceived quality, while a negative effect was observed for risk perception. The effect of risk perception was moderated by social trust and perceived quality. These results indicate that although the Brazilian GM food label policy is aligned with similar policies in developed countries, it has been implemented without an adequate disclosure. The consumers had a high confidence with regards to the science and the government, reducing their risk perception. Our findings indicate that in order to improve the effectiveness of this food policy, the Brazilian Ministry of Health should invest in advertising the labels, targeting the elderly and individuals with lower levels of education.