The widespread use of telehealth, providing healthcare remotely, is hampered by various barriers. Dutch nurses currently working in practice never received education in this new way of healthcare delivery. Education is frequently suggested as a strategy to overcome barriers in telehealth use. However, the nature and effectiveness of such education has not yet been specified and tested in practice. In a previous study, we identified 14 nursing telehealth activities and accompanying competencies. In the current study, we established the effectiveness of training in these competencies on nurses' subjective knowledge, self-efficacy and usage of telehealth. A two-day tailored training program in nursing telehealth activities was evaluated in a Dutch context among 37 participants across three settings: (a) twelve primary care (PC), (b) fourteen homecare (HC) and (c) eleven hospital (H) nurses. In each team, telehealth knowledge significantly increased during the training sessions. In each team, nurses' telehealth self-efficacy also significantly increased 6–10 weeks after the training. After the training, the number of remote consultations increased from 2 to 12 in primary care, 12 to 35 in homecare and decreased from 28 to 17 in the hospital setting. We conclude that training nurses in telehealth activities contributes to their knowledge and self-efficacy.