Abstract Background A leadless pacemaker is a new concept in which a miniaturized pacing device is self-contained within the heart. Recently published data show that leadless pacemakers are associated with a decreased risk of major complications when compared with transvenous cardiac pacemakers. This seems to be of particular importance in children and young adults in whom various complications may occur during their lifetime. Case summary Herein, we report the successful implantation of Micra™ Transcatheter Pacing System in two children: 12-year-old boy and 13-year-old girl, along with a long-term follow-up. The children had indications for pacemaker implantation, however, with an expected low percentage of pacing due to paroxysmal nature of the third-degree atrioventricular block. The implantation procedures were performed in general anaesthesia. There were no complications. During the 2-year follow-up, there were no adverse events and the electrical parameters of the device remained stable. Pacing percentage was below 0.1%. Discussion Transvenous cardiac pacemakers improve quality of life and reduce mortality but may be associated with various short- and long-term complications, mainly related to the presence of transvenous leads and the pulse generator. Compared with adult patients, the implantation of conventional pacemakers in children is still a challenge, not only because of their smaller size but also due to continuing growth, as well as a higher rate of lead and device-related complications. We demonstrate that the implantation of leadless pacemakers in children is feasible and could be worth considering in certain clinical scenarios, especially when ventricular pacing is required rarely.