What effect does the nomination of a female top candidate have on voters? While the literature has investigated the effect of ordinary female candidates on voters, it is less clear how the nomination of female leading candidates affects voters. We argue that the nomination of women as top candidates of political parties has important effects on voter attitudes and behavior due to the nationwide visibility of top party candidates. More specifically, we expect that the nomination of a female leading candidate has positive effects on the mobilization of female voters, their political efficacy, and increases the electoral support of the party among female voters. To test our theoretical argument, we conduct an unexpected events during survey design analysis exploiting the nomination of Annalena Baerbock by the German Green Party as the party’s top candidate in the 2021 federal election. This nomination provides a unique opportunity to identify the causal effect of a female leading candidate nomination as it was entirely unclear whether Annalena Baerbock or the Greens’ male co-leader, Robert Habeck, would be nominated until the day of the official announcement. By leveraging a survey among more than 10,000 citizens that was in the field when Baerbock was nominated, we shed light on how her nomination affected voters.