This study presents a novel method for synthesizing circular olefin copolymers from ethylene and α-olefins, enabling a closed-loop lifecycle. The approach involves coordination copolymerization of ethylene and α-olefins combined with a functionalized chain-transfer agent, followed by modular assembly of resulting AB telechelic polyolefin building blocks via polycondensation. This results in ester-linked PE-based copolymers that retain the thermomechanical properties of PE-based materials and exhibit full chemical circularity through simple transesterification and enhanced adhesion to polar surfaces. The research addresses the challenge of producing circular ethylene/α-olefin copolymers, including high-volume linear low-density PE, high-value olefin elastomers, and block copolymers. The key innovation lies in the synthesis of AB-type telechelic PE building blocks with tailored molecular weight and high purity, which are then assembled into on-demand PE materials through polycondensation. This method allows for the production of circular LLDPE, POE, and OBC materials using industrially abundant feedstocks, ethylene and α-olefins such as 1-hexene or 1-octene. The synthesized materials demonstrate tunable thermal properties, comparable to commercial PE materials, and enhanced adhesion to polar surfaces. The study also demonstrates the closed-loop recycling of these materials through transesterification, with high recovery yields and minimal degradation. The results show that the ester linkages installed in the new rPO and rOBC materials enable desired end-of-life chemical circularity and advantageous polar-surface adhesion properties. The method offers a scalable and practical approach for the design and synthesis of a wide range of circular olefin copolymers and hybrid polyolefin materials with closed-loop recyclability.This study presents a novel method for synthesizing circular olefin copolymers from ethylene and α-olefins, enabling a closed-loop lifecycle. The approach involves coordination copolymerization of ethylene and α-olefins combined with a functionalized chain-transfer agent, followed by modular assembly of resulting AB telechelic polyolefin building blocks via polycondensation. This results in ester-linked PE-based copolymers that retain the thermomechanical properties of PE-based materials and exhibit full chemical circularity through simple transesterification and enhanced adhesion to polar surfaces. The research addresses the challenge of producing circular ethylene/α-olefin copolymers, including high-volume linear low-density PE, high-value olefin elastomers, and block copolymers. The key innovation lies in the synthesis of AB-type telechelic PE building blocks with tailored molecular weight and high purity, which are then assembled into on-demand PE materials through polycondensation. This method allows for the production of circular LLDPE, POE, and OBC materials using industrially abundant feedstocks, ethylene and α-olefins such as 1-hexene or 1-octene. The synthesized materials demonstrate tunable thermal properties, comparable to commercial PE materials, and enhanced adhesion to polar surfaces. The study also demonstrates the closed-loop recycling of these materials through transesterification, with high recovery yields and minimal degradation. The results show that the ester linkages installed in the new rPO and rOBC materials enable desired end-of-life chemical circularity and advantageous polar-surface adhesion properties. The method offers a scalable and practical approach for the design and synthesis of a wide range of circular olefin copolymers and hybrid polyolefin materials with closed-loop recyclability.