Online word-of-mouth (WOM) is one of the most important channels through which consumers acquire product knowledge, and it is considered more credible than marketing information provided by firms. A growing body of research on online WOM has been reported in academia. Prior studies have analyzed the effects of the volume and valence of online WOM on consumer behavior, as well as moderating factors such as product type and cultural differences. However, research examining the moderating effect of competing products' WOM characteristics remains limited. Accordingly, this study analyzed the effects of online WOM valence and WOM variance on movie box office revenue within the film industry, and further examined the moderating effects of the number of competing movies and the WOM valence of competing movies on these relationships. Specifically, data were collected over a 45-day period for 112 movies released in South Korea in 2017, yielding a total of 4,487 observations, which were analyzed using multiple regression analysis. The results showed that online WOM valence and WOM variance had positive effects on movie box office revenue. Additionally, as the WOM valence of competing movies became more positive, the positive effect of a movie's WOM characteristics on its box office revenue was weakened, whereas as the number of competing movies increased, the positive effect of a movie's WOM characteristics on its box office revenue was strengthened.