The internet has introduced new ways for people to spend their time, from sharing on social media to battling in multiplayer videogames to watching user-generated videos. But in China, the web is also giving a big boost to a more conventional leisure-time pursuit: reading novels.

Some 43% of China’s online population, or 297 million people, read novels online in 2015, according to a government report. The best-known authors have millions of followers. Their works are made into films, TV series, animations and games. In a country...