Background Emotional lability (EL) is frequent in school‐aged children with attention deficit hyperactivity disorder (ADHD) and is associated with more frequent comorbidities and more severe impairment. However, little research has investigated the association between EL, ADHD and comorbid symptoms in preschoolers. This study assessed dimensional EL in preschoolers and its link with ADHD symptoms (e.g. hyperactivity‐impulsivity and inattention) and behavioural and emotional problems (e.g. aggression and anxiety). Method One hundred and fifty‐four preschoolers aged 3–6 years old were rated on questionnaires by parents. EL was assessed with the index from the Conners Rating Scale‐Revised and behavioural and emotional problems with an adapted version of the Social Behavior Questionnaire. Multiple linear regressions analyses were conducted. Results Higher EL was associated with higher hyperactivity‐impulsivity, inattention, anxiety and aggression problems. After controlling for other behavioural and emotional problems and sociodemographic variables, EL remained associated with hyperactivity‐impulsivity and anxiety. Conclusions Emotional lability seems to be a potential marker for ADHD symptoms with internalizing problems in preschoolers and could be a target for diagnosis and early interventions. This finding should be treated with caution as the study was limited by the low response rate of the participants and consequently the small sample size.