Riedel shear structures (RSS) are often observed in the embryonic stage of strike-slip fault development, which can be depicted in the field through outcrops and co-seismic surface ruptures. It is a critical concept linking the geomechanical behavior of individual earthquakes to structural geology at both local and regional scales. However, the influence of long-term fluid injections on the developing process of RSS, as manifested by the common occurrences of injection-induced earthquakes, has been rarely addressed. Here we document for the first time subsurface RSS expedited by long-term wastewater disposal injections in western Canada. We study an earthquake sequence consisting of 187 events (ML ranging 1.3–3.9) between 2018/01/01 and 2021/07/15 in an area without any previous seismic history. According to 31 well-constrained focal mechanism solutions, the injection-related earthquake sequence exhibits various faulting types with the vast majority (87%) being compatible with the background stress regime. The orientation of derived nodal planes collectively indicates a model of RSS that consists of four primary strike-slip structures striking 19º (R’), 79º (R), 94º (PDZ) and 109º (P), respectively. Moreover, six fault segments delineated from the relocated local seismicity are parallel to the sub-structures of RSS. Mohr-Coulomb failure analysis further suggests a cumulative stress perturbation of up to 10.0 MPa. Our observations suggest that long-term fluid injection can expedite the development of local fault systems. Therefore, it is probably important to consider the dimension of local/regional RSS in the assessment of the overall seismic hazard due to fluid injections.