Background: Coronary heart disease accounts for the leading cause of death and disability in the world, causing the deaths of 9.4 million people a year. About 1.9 million (or 21%) of these deaths are related to tobacco use and secondhand smoke (SHS) exposure. Secondhand smokers’ awareness of myocardial infarction (MI) is thought to impact the burden of disease, prevention, and time management. Hence, promoting more awareness of MI risk factors among secondhand smokers is incredibly important. Objectives: The study aimed to assess the level of awareness regarding MI risk factors among secondhand smokers. Methods: The study was conducted at Dr. M.G.R Educational and Research Institute, India, using a quantitative approach and descriptive research design. A sample of 508 subjects, using self-structured knowledge questionnaires, was selected for data collection and analysis. The study excluded patients with mental retardation, previous history of percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass graft surgery (CABG). The study plan was submitted to the Institutional Ethics Committee (IEC), and ethical clearance was granted. Results: A total of 508 respondents participated in this study, of whom 54.7% were females and the rest 45.3% were males. The majority, 55.5% of them, were in the age group of 20–29 years, followed by 11.6% in the age group of 30–39 years, 20.7% in the age group of 40–49 years, 8.9% in the age group of 50–59 years, and 3.3% in the age group of >60 years. Most participants, 272 (53.6%), had bachelor’s degrees as their highest educational level, followed by 36.6% from high school and 9.8% illiterate. We performed a multivariate logistic regression analysis to identify the demographic factors affecting the awareness of MI risk factors (secondhand smoking) and found that the age of 30–39 years [odds ratio (OR), 3.01; 95% confidence interval (CI), 1.13–8.01; p < 0.05], illiterate (OR, 2.33; 95% CI, 1.08–5.01; p < 0.05) were the factors affecting the recognition of acute MI risk factors (SHS). Conclusion: In our study, we conclude that females, age group of 30–39 years and >60 years and illiterate were unaware of risk factors of MI among secondhand smokers. To enhance the awareness of MI risk factors among secondhand smokers in India, education and promotion must be conducted with consideration of gender, age, education level, and occupation. Moreover, active engagement by the government, educational institutions, and medical institutions are required for awareness of both modifiable and non-modifiable MI risk factors.