Stay-cable forces in cable-stayed bridges without backstays may deviate from their design values during service, compromising safety and motivating regulation. This paper reports an in-service cable-force regulation project for the Jinzhou Bridge. A previous study characterized the in-service state of the bridge, determined its reasonable target state, and established and calibrated the corresponding finite element (FE) models; these results are adopted here as the research baseline. The maximum measured cable-force deviation was 78.95%, occurring in cable C2. The present study focuses on the stage-by-stage transition between the prescribed in-service and target states. Two opposite regulation sequences were evaluated stage by stage through FE simulations: Scheme A (from short cable C1 to long cable C9) and Scheme B (from long cable C9 to short cable C1), with the intermediate cable-force redistribution and the corresponding stress and deformation responses of the girder and tower examined at each stage. After satisfying the prescribed strength and alignment constraints, Scheme B was selected for field implementation because of its smaller process-induced cable-force fluctuations. The effect of the regulation sequence was particularly pronounced for the long cables C8 and C9, whose standard deviations under Scheme A were approximately 3.5 and 5 times those under Scheme B, respectively. Under Scheme B, the reductions applied to individual cables at their regulation stages ranged from 1856 to 14,646 kN. The required anchor-cup pullout control values ranged from 16.6 to 383.9 mm. The proposed framework advances the analysis from prescribed-state determination to constrained transition-path design and provides an implementable approach for in-service cable-force regulation of cable-stayed bridges without backstays.