The coronavirus disease 2019 (COVID-19) pandemic significantly affected the lives of Japanese collegiate men's basketball players. To describe the incidence of lower extremity injuries in Japanese collegiate men's basketball during the COVID-19 pandemic and examine the effects of the pandemic on injury patterns. Descriptive epidemiological study. Using data from a surveillance project of the Department of Medicine and Science of the Kanto Collegiate Basketball Federation, the authors included data from 6 men's basketball teams during the 2020-21 and 2021-22 seasons (11 team seasons). Injury rates per 1000 athlete-exposures (AEs) were calculated according to injury type, location, and frequency. Injury burden was estimated by multiplying the injury rate by the mean days lost. Injuries from the 2020-21 to 2021-22 seasons were compared with those before the pandemic (2013-14 to 2019-20 seasons) using injury rate ratios (IRRs), with significant differences indicated when the 95% CI did not include 1.0. In total, 135 lower extremity injuries were reported during 27,249 AEs. The overall injury rate of the 2020-21 to 2021-22 seasons was significantly higher than that of the 2013-14 to 2019-20 seasons (IRR, 1.37; 95% CI, 1.12-1.67). Lateral ankle sprains (IRR, 1.37; 95% CI, 1.02-1.86), hamstring strains (IRR, 2.86; 95% CI, 1.34-6.12), jumper's knee (IRR, 2.68; 95% CI, 1.13-6.37), and stress fractures of the proximal fifth metatarsal (IRR, 7.16; 95% CI, 1.31-39.08) were significantly higher during the 2020-21 to 2021-22 seasons compared with the 2013-14 to 2019-20 seasons. The rate of lower extremity injuries increased significantly in Japanese collegiate men's basketball players during the COVID-19 pandemic. The results of this study emphasize the importance of optimal screening and specific loads for injury prevention when detraining periods are anticipated.