As a precipitation-strengthened nickel-based superalloy, GH4169 undergoes a gradual transformation of the γ″ strengthening phase into the δ phase during long-term service at temperatures above 650 ℃, resulting in significant degradation of its high-temperature strength. For components subjected to long-term service, the residual yield strength after high-temperature exposure is a fundamental parameter for evaluating their load-bearing capacity and fatigue life. However, the quantitative correlations among high-temperature precipitate transformation, morphological evolution, and residual strength degradation remain insufficiently understood. To address this issue, the precipitate evolution and yield strength variation of GH4169 alloys with three different initial microstructural states, namely the commercial, standard heat-treated, and improved states, were systematically investigated before and after high-temperature aging. The results showed that aging at 800 ℃ significantly promoted the transformation of the γ″ phase into the δ phase. The commercial and standard heat-treated samples were mainly characterized by intragranular precipitate coarsening and the growth of needle-like δ precipitates, whereas the improved sample primarily exhibited slow coarsening of grain-boundary δ precipitates. Based on the microstructural characterization results, a yield strength model incorporating the transformation of the γ″ phase into the δ phase and the morphological evolution of non-spherical precipitates was established using experimentally measured microstructural parameters, including grain size, matrix composition, precipitate size and volume fraction, and dislocation density. In the model, Nb-rich precipitates were classified according to their morphology and size into nanoscale γ″ precipitates, granular or short-rod precipitates, and needle-like δ precipitates, and their strengthening contributions were evaluated separately. The predicted yield strengths agreed well with the experimental values at room temperature and 650 ℃, with errors below 8%. The results provide a microstructure-parameterized approach for evaluating the residual strength of GH4169 alloy after long-term high-temperature exposure.