It is our great pleasure to welcome you to The 4th ACM International Symposium on Blockchain and Secure Critical Infrastructure (BSCI 2022). Under extenuating circumstances due to Covid- 19, BSCI 2022 will be fully virtual, instead of the planned May 30th to June 2nd, 2022, in Japan. This is the fourth symposium organized as part of ACM AsiaCCS, which builds on success of the first edition in New Zealand. Proceedings from prior years can be viewed via https://dblp.org/db/conf/bsci/index.html. Despite the additional challenges due to the pandemic, this symposium still serves as a platform to share and discuss state-of-the-art research advances on blockchain and secure critical infrastructure, ranging from security and privacy issues in blockchain to attack methods on Blockchain to securing the smart grid, and so on. As part of the discussion, we hope to foster new, cutting-edge research collaboration between researchers and practitioners with complementary interests and background. BSCI 2022 attracted a total of 36 submissions, and all submissions were subject to rigorous reviews by subject matter experts. Eventually only 12 submissions were accepted for oral presentations and to appear in the symposium as regular papers (i.e. acceptance rate is 30%). We are also pleased to announce the following best paper and best student paper awards, based on the review feedback and ratings.