Voters need to be at least aware of candidates to hold them accountable. How does this work in mixed-member electoral systems where nominal votes often play a subordinate role and voters could entirely rely on party heuristics to choose between candidates? In lieu of existing causal explanations, we compile data on many factors contributing to candidate awareness and use a data-driven approach to identify variables that strongly predict voters’ awareness of district candidates in the run-up of the German Federal Elections 2009, 2013 and 2017. We find factors that describe candidate-, voter-, and district characteristics politically to be important out-of-sample predictors in contrast to factors that describe them socio-demographically. Interestingly, we find that incumbency predicts candidate awareness, but it does not matter whether incumbents were elected nominally or via a party list. These findings can be a starting point for developing causal theories and have implications for our understanding of how voters perceive the different types of MPs a mixed-member electoral system generates.