In order to address the environmental issues triggered by rapid economic development, China aims to achieve carbon neutrality by 2060. For this purpose, fintech companies such as Alipay have launched many sustainable mobile applications based on national conditions to promote sustainable behaviour by Chinese citizen. This chapter will explore certain sustainable issues and the need for sustainable mobile applications in China. Moreover, it will focus on the role of Alipay’s game module, Ant Forest, which has quickly amassed a large number of users, with practical contributions delivered to environmental protection by Chinese society by planting trees. The gameplay offered by Ant Forest allows users to transform their sustainable behaviour into real trees. Thus, the meaningful engagement and diverse rewards constitute a gamification element of Ant Forest and finally make it the most successful sustainable application in China. This development will also be explained in this chapter.