We investigate how opportunistic early elections affect citizens’ perceptions of electoral integrity, satisfaction with democracy, and voting behavior, focusing on the 2024 Japanese General Election—the shortest interval between a prime minister’s appointment and an election call in Japanese history. Using a two-wave panel survey conducted before and after the election, we show that perceptions of op- opportunistic timing significantly shaped voters’ democratic attitudes. Government supporters were more likely to accept the official rationale of seeking a mandate, while opposition supporters overwhelmingly interpreted the snap election as op- opportunistic. Across partisan lines, however, viewing the election as opportunistic consistently reduced perceptions of electoral fairness, which in turn lowered satisfaction with democracy. Importantly, these fairness perceptions influenced vote choice: while no clear effect was detected in single-member districts, perceiving opportunism decreased the likelihood of voting for governing parties in the proportional representation tier, including among some government supporters and independents. Taken together, these findings highlight that when voters recognize opportunistic election timing, it undermines their perception of electoral integrity, weakens their satisfaction with democracy, and, under certain conditions, imposes electoral costs on incumbents.