Importance: Young children often fall ill, leading to concern among their caregivers and urgent contact with health care services. Objective: To assess the effectiveness and safety of video tutorials to empower caregivers in caring for acutely ill children. Design, Setting, and Participants: Caregivers calling the out-of-hours Medical Helpline 1813 (MH1813), Emergency Medical Services Capital Region, Denmark, and their children aged 0.5 to 11.9 years were randomized to video tutorials (intervention) or telephone triage by a nurse or physician (control) from October 2020 to December 2021 and followed up for 72 hours blinded to the intervention. Data were analyzed from March to July 2022. Intervention: The intervention group had the call disconnected before telephone triage and received video tutorials on managing common symptoms in acutely ill children and when to seek medical help. Caregivers could subsequently call MH1813 for telephone triage. Main outcomes and measures: The primary outcome was caregivers' self-efficacy, reported in an electronic survey the following day. Secondary outcomes were satisfaction, child status, assessment by a general practitioner or physician at the hospital, telephone triage, and adverse events during the 72-hour follow-up period. Results: In total, 4686 caregivers and children were randomized to intervention (2307 participants) or control (2379 participants), with a median (IQR) child age of 2.3 (1.3-5.1) years and 53% male distribution in both groups (2493 participants). Significantly more caregivers in the intervention group reported high self-efficacy (80% vs 76%; crude odds ratio [OR], 1.30; 95% CI, 1.01-1.67; P =.04). The intervention group received fewer telephone triages during follow-up (887 vs 2374 in the control group). Intention-to-treat analysis showed no difference in secondary outcomes, but per-protocol subanalysis showed fewer hospital assessments when caregivers watched video tutorials (27% vs 35%; adjusted OR, 0.67; 95% CI, 0.55-0.82). Randomization to video tutorials did not increase adverse outcomes. Conclusions and relevance: In this randomized clinical trial, offering caregivers video tutorials significantly and safely increased self-efficacy and reduced use of telephone triage. Children had fewer hospital assessments when caregivers watched videos. This suggests a future potential of health care information to empower caregivers and reduce health care utilization. Trial Registration: ClinicalTrials.gov Identifier: NCT04301206.