Developing wheat that acquires and uses phosphorus (P) more efficiently is a promising and low-cost solution for increasing grain yield and reducing P-related environmental impacts. The present study identified agronomic and physiological traits that contribute to genetic variation in the P acquisition, remobilization, and utilization efficiency of 11 wheat cultivars from southwest China grown in P-deficient purple lithomorphic soil (Olsen P = 4.7) with balanced (75 kg P ha–1) and excessive P (120 kg P ha–1) supplies. On average, soil P deficiency (-P) reduced root P uptake (17.0%-60.8%), P remobilization (33.9%-52.8%), dry mass yield (11.5%-39.2%), and grain yield (17.7%-54.4%). Balanced P (+P) increased grain yield via increased plant biomass rather than increased HI. –P increased phosphorus uptake efficiency (PUpE, 4.5-fold), phosphorus utilization efficiency (PUtE, 1.25-fold), and phosphorus use efficiency (PUE, 5.4-fold) compared with those under +P, and PUtE explained most (58.1%-60.8%) of the genetic variation in PUE under both -P and +P. The high root P uptake of P-efficient cultivars under -P was regulated by root surface area and root length density in the 0-10 cm soil layer but not in the 10-20 and 20-40 cm soil layers, suggesting that a topsoil foraging strategy is a more economical approach than deeper root exploration for increasing P uptake. Root P uptake before anthesis and P remobilization after anthesis were critical for increasing the PUtE of wheat, given that P-efficient cultivars showed higher Pn (net photosynthetic rate) and sucrose levels than P-inefficient cultivars. Pn reduction by -P resulted from decreased Gs and Ci, and high evapotranspiration under +P increased shoot P% by increasing root P uptake. Genetic variation in the source-to-sink ratio was observed in consequence of a +P-induced allometric increase in sucrose in leaves and kernels. Owing to these beneficial effects, +P increased the kernel N and P yields of the 11 cultivars by 9.9%-52.4% and 12.3%-48.8%, respectively. The findings of this study could help improve wheat in future breeding efforts and P management by identifying desirable P-efficient phenotypes in P-deficient farming systems.