We study the transmission of financial knowledge through digital platforms and its effects on users’ investment in stocks and performance. Leveraging a proprietary dataset from one of China’s largest digital platforms, we measure users’ acquisition of financial knowledge through various platform information channels. Using a quasi-experimental setting to instrumentalize the acquisition, we find that the acquisition substantially increases stock market participation and enhances the sophistication and performance of investment behaviors, especially for older, inexperienced, and less wealthy households. Thus, digitalization democratizes finance by providing low-cost and scalable financial education, empowering individuals to make investment decisions aligned with portfolio theory.