Abstract: Geological sequestration of carbon dioxide (CO₂) in deep coal seams is confronted by formidable reservoir challenges, encompassing high in-situ stress, pronounced heterogeneity, and complex thermo-hydro-mechanical-chemical (THMC) coupling. Conventional geophysical monitoring methods, constrained by limited spatio-temporal continuity, are inherently incapable of achieving continuous, high-resolution, multi-parameter dynamic perception within the wellbore and near-wellbore zones, thereby constituting a critical bottleneck for precise fluid imaging and early risk warning. Scrutinizing the monitoring demands specific to deep coal seam CO₂ storage, three semi-quantitative criteria are delineated, namely, permeability impairment, transient stress concentration, and signal masking under strong heterogeneity, revealing the core capability deficit in current monitoring frameworks: the absence of a continuous dynamic perception layer in the near-wellbore region. Addressing this capability gap, the engineering application logic of Distributed Fiber-Optic Sensing Sensing (DFOS) is reconceptualised. Its core value resides not in its role as an optional supplementary technique, but rather as an indispensable “critical perception layer” that bridges the key capability shortfalls of existing monitoring systems. Grounded in the distinctive physico-mechanical responses of deep coal reservoirs, namely, adsorption-dominated mechanisms, matrix swelling, and the dynamic evolution of micro-fractures, the adaptive pathways for Distributed Temperature Sensing (DTS), Distributed Acoustic Sensing (DAS), and Distributed Strain Sensing (DSS) in deep coal seam scenarios are systematically elucidated. DTS tracks injection profile evolution and thermo-hydraulic dynamics; DAS integrates a dual-modal mechanism encompassing passive microseismic detection and active time-lapse wavefield imaging; DSS targets matrix adsorption-induced swelling and in-situ reservoir deformation. Through a unified downhole platform, the synergistic integration of these three modalities facilitates in-situ “temperature-acoustic-strain” coordinated monitoring, thereby furnishing a pivotal technical means for resolving complex fluid-solid coupling mechanisms in coal seams. At the system level, DFOS is established as the core boundary constraint within the multi-scale joint inversion framework of the comprehensive “space-air-ground-well” three-dimensional monitoring network. The continuous, high-density downhole data acquired by DFOS furnish high-precision in-situ constraints for time-lapse seismic macro-plume imaging, cross-well electromagnetic fluid identification, and microseismic fracture activity monitoring, transforming the monitoring paradigm from the “coexistence of multiple isolated methods” to a “collaborative inversion system anchored by a continuous downhole timeline”. This integration offers a viable pathway to mitigate the non-uniqueness inherent in multi-source signal inversion under conditions of pronounced heterogeneity. Five core technical challenges confronting deep coal seam CO₂ storage monitoring are synthesised: reliable capture of weak signals within strongly heterogeneous preferential flow channels, accurate storage capacity quantification under non-negligible adsorbed-phase volume, inversion non-uniqueness driven by multi-field coupling, constraints imposed by full-lifecycle monitoring costs on commercialisation, and the absence of coal-seam-specific monitoring standards and regulatory frameworks. Correspondingly, six prospective research directions are delineated: refining the integrated “space-air-ground-well” observation system, establishing a “one-cable-multi-measurement” multi-modal joint detection methodology, elucidating coal-seam-specific fibre-optic response mechanisms, reinforcing DFOS as the core constraint in joint inversion, developing low-cost modular application schemes, and constructing a long-term standardised application framework. Collectively, these findings furnish a systematic methodological framework for bridging the technical gap in near-wellbore dynamic perception and advancing high-precision, cost-effective dynamic monitoring and long-term safety early-warning systems for deep coal seam CO₂ sequestration.