Purpose: To estimate the time to resolution of COVID-19 symptoms and identify associated factors among COVID-19 patients. Methods: A prospective study was conducted with 2777 adults identified with SARS-CoV-2 infection between March and December 2020 at the Centro Hospitalar Universitário de São João. Data collected between November 2020 and April 2021 included sociodemographic, clinical, and infection-related variables. We used survival analysis to estimate the time until symptom resolution, and Cox regression identified associated factors using crude (HR) and adjusted hazard ratios (aHR). Results: Symptom resolution was not experienced by 36.5% of participants within the study period. Higher hazards of symptom resolution were observed among males [aHR:1.55, 95% Confidence Interval (CI):1.41–1.70], those with master/doctoral education (aHR:1.29, 95% CI:1.08–1.54), and better income perception. Lower hazards were seen in adults aged 40–49 (HR:0.79, 95% CI:0.68–0.93) and 50–59 (HR:0.76, 95% CI:0.65–0.90), individuals with comorbidities (aHR:0.83, 95% CI:0.74–0.92), and those hospitalised during the acute phase (aHR:0.71, 95% CI:0.61–0.82). Conclusions: Over one-third of COVID-19 patients had unresolved symptoms months post-infection. Middle age, female sex, lower education, poor income perception, comorbidities, and hospitalisation in the acute phase were the most significant predictors for non-resolving symptoms, underscoring the need for targeted interventions.