This study estimates the impact of third-party online payment systems on trade, export, import, and Internet retailing in China. Also, the study examines the financial development mechanism via which third-party payment affects trade, export, import, and Internet retailing in China. By employing a sample of 31 provinces in China covering 2011 to 2018, the findings indicate that, third-party payment drives China’s trade (0.43%), export (0.42%), import (0.47%), and Internet retailing (0.24%). The study also finds that third-party payment complements financial development to positively affect trade, export, import, and Internet retailing in China. The study recommends policymakers promote third-party payment development in China to boost trade, export, import, and Internet retailing.