Policymakers’ incentives during election campaigns can lead to decisions that significantly affect deforestation. Yet this is rarely studied. For Brazil’s Atlantic Forest, a highly biodiverse tropical forest, we link federal-and-state as well as municipal elections to annual deforestation between 1991 and 2014. Across 2253 municipalities, those with higher deforestation see a significant rise in deforestation during federal-and-state election years. Municipal election years raise deforestation for locations with lower deforestation, whereas all of these increases are accentuated when there is party alignment between different levels of government. This effect of election cycles has fallen over time, to date, yet that cannot be assumed to continue. Our results highlight the need to limit opportunistic behaviors that affect natural resources and the environment with implications for biodiversity, carbon storage, and other ecosystem services.