In low- and middle-income countries, poverty and impaired growth prevent children from meeting their cognitive developmental potential. There are few studies investigating these relationships in high-income settings. Participants were 12,536 children born between 2000 and 2002 in the UK and participating in the Millennium Cohort Study (MCS). Short stature was defined as having a height-for-age 2 or more standard deviations below the median (≤ − 2 SDS) at age 3 years. Standardized British Abilities Scales II (BAS II) language measures, used to assess language development at ages 3, 5, 7 and 11 years, were the main outcome assessed. Children with short stature at age 3 years (4.1%) had language development scores that were consistently lower from ages 3 to 11 years (− 0.26 standard deviations (SD) (95% CI − 0.37, − 0.15)). This effect was attenuated but remained significant after a