A prospective study at Honghui Hospital, Xi'an Jiaotong University investigated the relationship between preoperative hypoalbuminemia and postoperative subsyndromal delirium (SSD) in elderly hip fracture patients. Hypoalbuminemia was defined as a serum albumin level below 35 g/L and was noted in 60 of 279 patients (21.51%). Postoperative SSD occurred in 114 patients (40.86%). Multivariate logistic regression analysis showed that hypoalbuminemia was independently associated with an increased risk of SSD (OR = 6.13, p < 0.001), as were diabetes mellitus (OR = 2.93, p = 0.007) and smoking (OR = 4.30, p = 0.033). Each one-point increase in MMSE score was associated with a decreased risk of SSD (OR = 1.74, p < 0.001). The threshold effect of the association between albumin levels and SSD was confirmed with continuous transformation (p = 0.034). Out of 279 patients, 22 were admitted to the ICU. The study recommends preoperative interventions to correct hypoalbuminemia.