Environmental conservation and economic advantages have propelled the swift expansion of the remanufacturing industry. Many original equipment manufacturers (OEMs) delegate remanufacturing operations to third-party remanufacturers (TPRs) through outsourcing and authorization. Furthermore, blockchain technology enhances consumers’ intention to purchase remanufactured products by disclosing more product information. To investigate the impacts of blockchain on remanufacturing mode selection, this paper focuses on a competitive remanufacturing supply chain comprising an OEM and a TPR under a cap-and-trade policy. Further, four game-theoretic models are derived from whether to adopt blockchain technology and which remanufacturing mode to select. Three major findings are obtained by solving and comparing the four models: (1) Adopting blockchain does not consistently result in advantages for both the OEM and TPR, and they should adopt blockchain for information disclosure in instances where the unit blockchain adoption cost is low, and the disclosure degree of remanufactured product information is also low. (2) Compared with not adopting blockchain technology, if the unit blockchain adoption cost is low, blockchain technology will increase the remanufactured product sales, thereby fostering the advancement of remanufacturing and contributing to reducing the environmental impact. (3) Whether blockchain is adopted or not, the OEM always tends to be in the outsourcing remanufacturing mode. The TPR only opts for the outsourcing remanufacturing mode when consumers’ preference for remanufactured products is high. More importantly, adopting blockchain will likely enhance consumers’ preference for remanufactured products, potentially shifting the TPR’s inclination for remanufacturing mode from authorization to outsourcing in some instances.