Background Subjective wellbeing (SWB) is a self-reported positive life judgment and good feeling. RHD, rheumatic heart disease, is a long-term sequel of single or recurrent acute rheumatic fever. There are no studies that assessed SWB in RHD patients. We aimed to assess SWB among RHD subjects enrolled in chronic care at Tikur Anbessa Specialized Hospital (TASH), Ethiopia. Methods This observational cross-sectional study employed a validated Amharic WHO-5 wellbeing index to assess SWB. Sociodemographic and clinical data were collected using structured questionnaire. RHD subjects aged 9 years and above were included. Factors associated with SWB were assessed using logistic regression models. Results The study included 384 subjects, females 68.2% (262). Children, < 18 years, constituted one third of study subjects, 32.8% (126). Moderate and severe echocardiographic RHD dominated, 85.9% (330) with no associated comorbidity, 84.4% (324). Only 17.2% (66) had surgical or device intervention. Poor SWB was documented in 9.6% of study subjects (95% CI: 6.88–13.04). On multivariable regression, those with younger age RHD diagnosis, < 20 years, had almost three times higher odds of poor SWB, adjusted odds ratio (aOR) 2.69(95% CI: 1.30–5.58, P 0.008). Those with monthly family income of < 1000 Ethiopian Birr had three times higher odds of poor SWB, aOR 2.97(95% CI: 1.24–7.1, P 0.014). Study subjects who had good medication adherence had reduced odds of poor SWB, aOR 0.37(95% CI: 0.18–0.77, P 0.028). Those who received psychologic support from their families also had reduced odds of poor SWB, aOR 0.26(95% CI: 0.11–0.64, P 0.003). Conclusion Poor SWB was documented in one-tenth of RHD patients. Family income, younger age at RHD diagnosis, medication adherence and psychological support predicted poor SWB. Poor SWB has to be considered and assessed among RHD patients particularly among those with younger age at RHD diagnosis and poor family income. Further mixed studies are recommended to assess how medication adherence and psychological supports associate with positive SWB among RHD patients.