Oxidative stress generated nucleoside damage seems to represent key pathophysiological mechanisms of bipolar disorder (BD). Likewise, mood and activity are core features of BD and can be reliably monitored using smartphone-based applications. The aim was to investigate whether oxidative stress generated nucleoside damage could reflect psychopathology in BD using easily available and non-invasive patient-reported smartphone-based symptoms. We included 223 patients newly diagnosed with BD and employed linear mixed-effect regression models to associate baseline measurements of 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) levels with patient-reported smartphone measures of mood, activity, anxiety, stress and sleep duration monitored three days prior to and 30 days after the baseline visit in the longitudinal Bipolar Illness Onset Study. In patients newly diagnosed with BD higher 8-oxoGuo levels were inversely associated with the patient-reported activity level (B = 0.953, 95%CI = 0.909;0.99, p = 0.043) and positively associated with patient-reported anxiety (B = 1.104, 95%CI = 1.022;1.161, p=0.012), perceived stress (B = 1.092, 95%CI = 1.009;1.183, p = 0.014) and sleep duration (B = 1.000, 95%CI = 1.000;1.001, p = 0.001), respectively, in analyses, adjusted for sex and age. The associations between 8-oxoGuo levels and anxiety, perceived stress and sleep duration, respectively, withstood adjustment for sex, age, smoking, BMI and alcohol intake. No associations between 8-oxodG levels and patient-reported smartphone-based data were found and mood was not associated with 8-oxoGuo. Oxidative stress was associated with patient-reported smartphone-based data on activity, anxiety, stress and sleep duration pointing towards that oxidative stress generated nucleoside damage may reflect ongoing psychopathology in BD.