SARS-CoV-2 infection can result in long COVID, characterized by post-acute symptoms from multiple organs. Current hypotheses on mechanisms underlying long COVID include persistent inflammation and thromboembolism; however, compelling evidence from humans is limited and causal associations remain unclear. In this study, we tested the association of thromboembolism-related genetic variants with long COVID in the Long COVID Host Genetics Initiative (ncases = 3,018; ncontrols = 994,582). Primary analyses revealed that each unit increase in the log odds of genetically predicted venous thromboembolism risk was associated with 1.21-fold odds of long COVID (95% confidence interval (CI): 1.08-1.35; P = 1.2 × 10-3). This association was independent of acute COVID-19 severity, was robust across various sensitivity analyses and was replicated in external datasets. Downstream analyses using gene-specific instruments, along with protein and gene expression data, suggested the protease-activated receptor 1 (PAR-1) as a potential molecular contributor to long COVID. These findings provide human genetic evidence implicating shared pathogenetic pathways in thromboembolism and long COVID.