Objectives: This study aimed to investigate the interrelation between slowing in walking, thinking and mood, and their relationship with cerebral small vessel disease (CSVD) in a geriatric population. Design: Cross-sectional study. Setting and Participants: 566 geriatric outpatients from the Amsterdam Aging Cohort (49% female; age 79 ±6 years), who visited the Amsterdam UMC geriatric outpatient memory clinic. Methods: Patients underwent a comprehensive geriatric assessment, brain imaging, and a neuropsychological assessment as part of medical care. Three slowing aspects were investigated: gait speed, processing speed, and apathy symptoms (higher scores indicating more advanced slowing). We visually rated CSVD [white matter hyperintensities (WMHs), strategic lacunes, and microbleeds] on brain imaging. Results: Regression analyses showed that slowing in walking (gait speed) was associated with slowing in thinking [processing speed; β = 0.35, 95% confidence interval (CI) 0.22, 0.48] and slowing in mood (apathy symptoms; β = 0.21, 95% CI 0.13, 0.30), independent of important confounders. Large confluent areas of WMH (Fazekas 3) were associated with all slowing aspects: gait speed (β = 0.49, 95% CI 0.28, 0.71), processing speed (β = 0.36, 95% CI 0.19, 0.52) and apathy symptoms (β = 0.30, 95% CI 0.09, 0.51). In addition, in patients with more slowing aspects below predefined cutoffs, severe WMH was more common. Presence of ≥3 microbleeds was associated with apathy symptoms (β = 0.39, 95% CI 0.12, 0.66), whereas lacunes were not associated with slowing. Conclusions and Implications: This study provides evidence that slowing in walking, thinking, and mood are closely related and associated with CSVD. This phenotype or geriatric syndrome could be helpful to identify and characterize patients with CSVD.