<p>Hydraulic fracturing (HF) for Enhanced geothermal systems is conducted in diverse geological settings and rock masses, where the HF development strongly depends on the hydro-mechanical properties of the host rock. The characteristics of these stimulated fracture networks can vary significantly depending on rock types. In this study, we investigated variations in HF processes in crystalline (granite) and sedimentary (sandstone) rocks using real-time active and passive seismic monitoring systems. Application of the joint active–passive monitoring system assisted in a better understanding of the seismic and aseismic fracturing processes associated with HF in granite and sandstone. The study involved laboratory HF testing of true triaxially loaded Barre granite and Lyons sandstone cubes, with combined real-time active and passive seismic monitoring using high-viscosity gear oil. Passive monitoring successfully mapped the generated HF geometry, revealing a tortuous and branching HF in granite and a more planar HF in sandstone. The number of detected microseismic events was relatively greater in granite, along with lower <i>b</i>-values (frequency-magnitude distribution), indicative of a relatively lower proportion of small-magnitude microseismic events. This points to a more heterogeneous HF process, where variations in mineral composition and the presence of pre-existing microcracks caused uneven stress redistribution and diverse crack-growth behaviors. The analysis of crack source mechanisms via moment-tensor inversion indicated a slightly lower proportion of tensile openings in granite, consistent with mixed-mode HF initiation and propagation. The sensitivity of active signals’ attributes (velocity and amplitude) was significantly greater for the HF processes in granite compared to sandstone, indicating much stronger variations in the elastic properties of the granite. The initial aseismic deformation and fluid leak-off were notably prominent in granite specimens. While the active signals’ amplitude fluctuated for both granite and sandstone, the changes were significantly larger in granite. Overall, the combined active–passive seismic approach enabled clear discrimination of HF processes, demonstrating that crystalline rocks undergo more distributed fracturing and complex HF growth than sedimentary rocks. These findings provide insight into how rock-type-specific HF mechanisms influence stimulated rock volume and seismic response, offering guidance for improved monitoring, interpretation, and optimization of field HF operations in geologically diverse EGS reservoirs.</p>