Background/Objectives: The neuroprotective role of dietary choline during adulthood has not yet been conclusively proven. This study aims to investigate the influence of long-term choline and its constituent intakes on cognitive decline in the Chinese population. Methods: A total of 4502 subjects (≥55 years) with at least two waves of completed data and without cognitive decline at baseline were selected from the China Health and Nutrition Survey 1997–2018. Three consecutive 24 h dietary recalls were performed to collect dietary intake information for choline, phosphatidylcholine (PC), and glycerophosphocholine (GPC) measures. Several items from the Telephone Interview for Cognitive Status (Modified) were employed to perform a cognitive assessment. Cox frailty models were used to estimate hazard ratios (HRs) and 95% CIs. Results: A total of 783 participants developed cognitive decline during 26,080 person-years of follow-up. Cumulative average intakes of choline, PC, and GPC were 188.0, 126.7, and 17.1 mg/d, respectively. In the total population, after full adjustment, subjects in the lower (Q2), medium (Q3), higher (Q4), and highest (Q5) quintiles of dietary choline showed 27.8% (95% CI: 0.584, 0.894), 33.9% (95% CI: 0.522, 0.836), 23.0% (95% CI: 0.599, 0.990), and 29.3% (95% CI: 0.526, 0.949) decreases in the risk of cognitive decline compared to the lowest (Q1), respectively. Similar results were observed in PC but not GPC measures. Both higher choline and PC intakes induced a lower risk of cognitive decline for subjects ≥ 65 years at baseline (Q3 and Q4) and females (Q2–Q5). A marginally significant association of GPC was found for subjects ≥ 65 years (Q5) and males (Q4). Conclusions: These findings identify age and gender disparities relating to the protective associations of dietary choline, PC, and GPC with incident cognitive decline in middle-aged and older Chinese populations.