Problematic smartphone use (PSU) is associated with several types of psychopathology, such as depression and anxiety severity. However, the majority of studies reporting these associations have not used objective smartphone use data and/or repeated-measures study design. Our aim was to investigate how self-reported levels of PSU, depression, anxiety, and daily depressive mood relate to objectively measured smartphone use over one week. We assessed objective smartphone use by daily minutes of screen time and number of phone screen unlocks. One hundred and one undergraduate university students participated. Bivariate correlations and latent growth curve analyses showed that PSU severity related to screen time minutes, but not to phone screen unlocking. Depression and anxiety severity were not related to screen time minutes, but negatively correlated with frequency of phone screen unlocking. Additionally, daily depressive mood items did not, in general, predict objective smartphone use for the corresponding day. However, average daily depressive mood over one week positively correlated with PSU levels. These findings and their implications are discussed.