The goal of allowing citizens to participate in local government’s decision-making process is to enhance fiscal transparency and accountability. Under the accrual-based accounting system, however, mayors of local governments have substantial discretion in estimating accounting numbers, as well as political incentives to manage performance in order to appease voters. Accordingly, such participation may fail to achieve its intended objective. Utilizing a unique dataset of 220 Korean local governments’ accrual-based financial statements for 2015-2018, we examine the effect of citizens’ participation in the budgeting process on financial reporting quality and how the effect varies with political competition in local municipalities. We first do not find any significant association between the level of participatory budgeting institutions and financial reporting quality measured by the allowances for uncollectible taxes. This finding is consistent with the countervailing effects involved in the participatory budgeting system (i.e., citizens’ enhanced access to accounting information versus mayors’ opportunistic incentives). However, we find that this relation hinges on the level of municipal political competition, captured by the gap in votes obtained by the incumbent mayor and the second-place candidate in the election. The relation becomes significantly positive when political competition is weaker. This evidence implies that mayors’ political incentives and concerns about re-election dominate the monitoring role of citizen councilors, consequently reducing fiscal transparency. Overall, our results suggest that political competition dampens the positive effect of participatory budgeting on the financial reporting quality of local governments.