Herein, we present a proof-of-concept investigation into the assessment of the laccase-like activity of covalently bonded carbon environments connected to Fe-N sites, using the closed π conjugated phthalocyanine-based intrinsic covalent organic polymers (COP) with well-designed structures. Based on the theoretical prediction and experimental implementation, the impact of the covalent-bonded carbon matrix on the laccase-like activity of COP-X (X represents the degree of conjugation) was systematically investigated. Further calculation results by density functional theory showed that the strongest laccase-like catalytic activity of COP-2 may be due to the facile desorption of catalytic intermediates, and the laccase-like catalytic mechanism of COP-2 nanozymes was also deeply understood. As anticipated, the utilization of COP-2 nanozymes with laccase-like activity enabled the achievement of excellent sensitivity for monitoring epinephrine in human serum. In addition, the COP-2 nanozymes also facilitate the detection and degradation of phenolic pollutants present in the environment. This finding presents a novel perspective for the rational design of high-performance laccase-like iron based nanozymes, and also lays the foundation for clarifying the origin of the laccase-like activity of nanozymes.