attractive applications in organic lightemitting diodes (OLEDs), [2] high-sensitivity chemical sensing, [3,4] space/time-resolved information encryption, [5] high-resolution biological imaging, [6] optical recording, [7] and so forth. [8] Currently, high-efficiency and long-lived RTP materials are primarily limited to inorganic and metal-containing compounds. In particular, the intrinsic disadvantages of metal resources, such as their high cost and complex preparation processes, predominantly hinder their diverse range of applications. [9] Pure organic RTP materials have received considerable attention owing to their superior performance in terms of affordability, adequate biocompatibility, facile modification of functional groups, simple synthesis, and unique features of flexibility, elasticity, and transparency. [10] However, the phosphorescence process initiating from the lowest excited singlet state (S 1 ) to the triplet state (T) through intersystem crossing (ISC), and thereafter, the generated triplet excited state (T 1 ) to the ground state (S 0 ), is spin forbidden. [11] Moreover, the excited triplet state is readily deactivated by nonradiative vibrations and quenched with molecular oxygen. Therefore, the realization of long-lived RTP under atmospheric conditions at room temperature remains a considerable challenge, even in aqueous environments.In recent years, several effective strategies have been employed to improve the spin-orbit coupling (SOC) and suppress the nonradiative decay. For instance, the introduction of heteroatoms such as N, O, S, or aromatic carbonyl groups into organic systems is beneficial for promoting ISC. [12] Furthermore, crystallization, [13,14] host-guest interactions, [15] polymerization, [16] charge separation, [17] and organic-doped inorganic systems [18,19] have been utilized to minimize nonradiative deactivation and stabilize triplet excitons. Ma et al. [20] employed binary copolymerization of diallyl terephthalate and acrylamide to develop amorphous pure organic polymer materials with a phosphorescence lifetime of 537 ms. Yan et al. [21] developed a new smart RTP film that exhibited direct white-light-emitting polarized phosphorescence. The geometric confinement effect and abundant intermolecular hydrogen bonding between the Room-temperature phosphorescence (RTP) materials have garnered considerable research attention owing to their excellent luminescence properties and potential application prospects in anti-counterfeiting, information storage, and optoelectronics. However, several RTP systems are extremely sensitive to humidity, and consequently, the realization of long-lived RTP in water remains a formidable challenge. Herein, a feasible and effective strategy is presented to achieve long-lived polymeric RTP systems, even in an aqueous environment, through doping of synthesized polymeric phosphor PBHDB into a poly(methyl methacrylate) (PMMA) matrix. Compared to the precursor polymer PBN and organic molecule HDBP, a more rigid polymer microenvironment and electrostatic int...