Hypnoanalgesia is a promising non-pharmacologic adjunct technique in paediatric interventions. Its safety, efficiency, and impacts on paediatric cardiac catheterisation (CC) are unknown. Methods: In a prospective study, patients aged <16 years who underwent CC under hypnoanalgesia from January to December 2021 were included. Pain and anxiety were assessed using the analgesia nociception index (ANI) and the visual analogue scale (VAS). Results: Sixteen patients were included; the mean age was 10.5 years, and the mean weight was 37 kg. Catheterisations were interventional in 10 patients (62.5%). Hypnoanalgesia indications were general anaesthesia (GA) contraindication in four patients (25.0%), the need for accurate pressure measurements in three patients (18.7%), and interventionist/patient preferences in nine (56.3%). CC was accomplished in 15 patients (93.7%), even in complicated cases. In one case, pulmonary artery pressures were normalised compared to previous catheterisation under local anaesthesia alone. The VAS score was under 5/10 for all patients. The ANI remained above 50 (no painful zone) for all but one patient. There was no significant decrease in the ANI during the intervention compared to the baseline (p = 0.62). No complications were reported. Conclusion: Paediatric CC is feasible and safe under hypnoanalgesia, even in complicated cases. Hypnoanalgesia was efficient in managing pain and stress, and it ensures more reliable pressure measurements.