Background In patients undergoing transcatheter aortic valve replacement (TAVR), those with small left ventricle (LV) may have an increased risk of poor outcomes, because small LV is associated with low‐flow (LF), left ventricular hypertrophy. However, the impact of small LV on patients undergoing TAVR remains unknown. Methods and Results We examined 2584 patients who underwent TAVR between October 2013 and May 2017 using data from the Japanese multicenter registry. On the basis of the American Society of Echocardiography guidelines, small LV was defined as left ventricular end‐diastolic dimension <42.0 mm for men or <37.8 mm for women. The 2‐year clinical outcomes were compared between patients with and without small LV using multivariable Cox regression analyses and propensity score matching. Subgroup analyses by LF, left ventricular hypertrophy were performed. Of 2584 patients who underwent TAVR, 466 (18.0%) had small LV. Patients with small LV had smaller body size and less comorbidity, and were more likely to have LF status compared with those without. Small LV was associated with a higher 2‐year all‐cause (20.8% versus 14.3%; adjusted hazard ratio [HR],1.58 [95% CI, 1.20–2.09]; P=0.0013) and cardiovascular mortality (8.8% versus 5.5%; adjusted HR, 1.93 [95% CI, 1.25–2.98]; P=0.0028). Propensity score matching analysis showed consistent findings. In subgroup analyses, LF, left ventricular hypertrophy did not interact with small LV. Conclusions Small LV, determined by a simple echocardiographic parameter, was associated with poorer clinical outcomes after TAVR regardless of LF, left ventricular hypertrophy. LV size may be useful for assessing clinical outcomes after TAVR. Registration URL: https://www.umin.ac.jp/ctr/index.htm; Unique identifier: UMIN000020423.