Abstract Background: Whether changes in 25 hydroxy vitamin D3 (25(OH)D3) levels after colorectal cancer diagnosis influence clinical outcomes is unclear. We investigated the association of trajectories of 25(OH)D3 levels with recurrence and all-cause mortality. Methods: In total, 679 patients were included in our data analyses. Trajectories of 25(OH)D3 levels were defined on the basis of vitamin D status at diagnosis, at 6 months, and 2 years after diagnosis. Observed trajectories of 25(OH)D3 levels were consistent deficient levels (20%), consistent sufficient levels (39%), increasing levels (20%), and a temporary drop in levels (13%). Associations of trajectories of 25(OH)D3 with recurrence and all-cause mortality were assessed using multivariable Cox proportional hazards regression models. Results: During a follow-up time of 2.2 years for recurrence and 3.5 years for all-cause mortality, 31 and 65 events occurred, respectively. No statistically significant associations were observed for vitamin D trajectories and the risk of recurrence. Patients who were consistently sufficient compared with patients who were consistently deficient had a lower risk of all-cause mortality [HR 0.39; 95% confidence interval (CI), 0.21–0.73]. The risk of all-cause mortality seems lower in patients with increasing levels or a temporary drop in levels (HR 0.54; 95% CI, 0.27–1.10 and HR 0.40 95% CI, 0.17–0.93) relative to patients with consistent deficient levels. Conclusions: Patients with colorectal cancer following a trajectory characterized by sufficient levels of 25(OH)D3 2 years after diagnosis all appeared to have a lower risk of all-cause mortality compared with patients having consistent deficient levels. Impact: Further studies should investigate how trajectories of 25(OH)D3 levels are associated with colorectal cancer recurrence.