<p>Nickel-based superalloys demonstrate exceptional mechanical strength stemming from their unique γ/γ′ microstructure. Understanding microstructural state effects on the strength of GH4742 superalloy is critical for mechanical performance. The investigation of GH4742 superalloy samples with controlled microstructure was conducted via a methodology combining tailored thermomechanical processing, heat treatment, and strengthening mechanism modeling. The γ + γ′ duplex structure achieves an optimal strength-ductility synergy, exhibiting yield strength of 805&#xa0;MPa, ultimate tensile strength of 1440 MPa, and elongation of 21%. Comparatively, samples containing fine single-modal γ′ precipitates exhibit marginally reduced performance, while mixed-grain structures containing grain boundary-localized columnar γ′ precipitates demonstrate severe property degradation (yield strength of 582&#xa0;MPa, ultimate strength of 1007&#xa0;MPa, elongation of 12%). Quantitative analysis indicates that mechanical responses are predominantly governed by multimodal γ′ precipitate distributions and their synergistic precipitation strengthening effects. Notably, the γ + γ′ duplex structure exhibits exceptional strengthening efficacy, with precipitation strengthening mechanisms contributing 670.83&#xa0;MPa to its overall strength.</p>