The blood coagulation enzyme factor Xa (FXa) is a particularly promising target for anticoagulant therapy, and identification of oral small-molecule inhibitors of FXa remains a research focus. On the basis of the X-ray crystal structure of FXa and its inhibitor rivaroxaban, we designed and synthesized a series of conformationally restricted mimics containing a novel [6,6,5] tricyclic fused oxazolidinone scaffold. Intensive structure-activity relationship (SAR) and structure-pharmacokinetic relationship (SPR) studies on this new series led to the discovery of compound 11a: a highly potent, selective, direct, and orally bioavailable FXa inhibitor with excellent in vivo antithrombotic efficacy and preferable pharmacokinetic profiles. Druggability evaluation of compound 11a was undertaken and elicited positive outcomes. All results indicate that compound 11a is a promising drug candidate for the prevention and treatment of thromboembolic diseases in venous and arterial systems.