To authoritarian rulers, holding somewhat competitive elections enhances legitimacy, but entails political risks. Committing electoral fraud can secure victory, but may jeopardize regime legitimacy. However, there is a tool of electoral manipulation that allows authoritarian rulers to reduce electoral risk while preserving legitimacy: gerrymandering. This article undertakes a systematic study of gerrymandering in Hong Kong, using a dataset that documents boundary changes at the level of residential buildings. The empirical findings show a significant partisan bias in electoral redistricting: opposition constituencies are more likely to be redistricted. Redistricting, however, fails to deter opposition incumbents from seeking re-election. No significant negative relationship is found between redistricting and opposition incumbents’ vote share, although redistricting does reduce their overall chances of re-election. The results suggest that gerrymandering, which involves the use of packing and cracking strategies in different districts, can be employed to undermine the aggregate electoral performance of the opposition parties.