Social media have increased the frequency and intensity of firm’s online controversial events, which differs conceptually from negative events. Despite this, there exists a dearth of research on the attributes of these events and how firms can effectively manage them. We present a theoretical framework that identifies two characteristics – namely, the information redundancy and asymmetry problem and the community norm problem within consumer groups- and introduce two expected user-generated content (UGC) strategies - the informativeness strategy and the norm contradiction strategy- that firms can employ. This paper presents an analysis of user-generated posts from online brand communities (OBCs) on two distinct Chinese social media platforms. It aims to provide the first empirical evidence to understand how and whether UGC strategies can help firms broaden favorable voice and its corresponding impact on consumer engagement. The analysis is based on a sample of 10,480 data points collected from Weibo and Zhihu. These findings indicate that firm-expected UGC strategies have a significant impact on consumer engagement. We also examine the moderating effect of platform context and time-related factors. Our work advances the knowledge on firms’ online controversial events and UGC and provides practical implications for firms to effectively manage online controversial events.