Obesity is a global health problem. In developing countries such as Zimbabwe, obesity is both an emerging health problem and a grey area, particularly among adolescents. This study assessed the prevalence of obesity and factors associated with low obesity awareness among adolescents. Method: A cross-sectional survey was performed using an interviewer-administered questionnaire. The participants were 423 adolescents aged 14–19 years recruited from 10 schools in Harare using a stratified random sampling technique. Data were analyzed using SPSS software (version 23) and binary logistics regression was used to examine the factors associated with low obesity awareness. The level of significance was set at p < 0.05. Results: The median± IQR age was 16 (14-18) years, and overweight and obesity affected 15.8% of the participants with higher proportions among girls (73.1%, p = 0.002). Low obesity awareness was observed in 27.1% of the adolescents with a higher proportion among girls (67.0%, p = 0.001), 14–16-year-olds (51.3%, p = 0.317), and obese adolescents (56.7%, p = 0.001). Significant factors associated with low obesity awareness were household heads lacking formal education [OR = 9.41 (2.20–40.36), p = 0.003] and inadequate (poor) food habits [OR = 2.58 (1.33–5.01), p = 0.005]. Conclusions: Our study showed that adolescents had different obesity awareness levels and diverse perceptions in terms of obesity causes, and a range of potential solutions. Obesity awareness and nutrition education should address adolescents’ poor eating habits while taking cognizance of the different education levels of household heads.