Background: The sharing of health information is invaluable for direct care provision and reasons beyond direct care, such as for health services management. Previous studies have shown that willingness to share health information is influenced by an individual’s trust in a healthcare professional or organisation, privacy and security concerns, and fear of discrimination based on sensitive information. The importance of engaging the public in policy and practice development relating to the use and sharing of health information has been identified as an essential step for countries to take. This study’s aim was to examine the factors that influence the Irish public’s willingness to share their health information as part of a national public engagement on health information. Methods: A qualitative study using online focus groups was conducted as part of a wider national public engagement on health information. Participants were purposively recruited from a combination of public, patient, and service user groups in Ireland. Focus group interviews were audio-recorded, transcribed verbatim and analysed using inductive content analysis. Results: In total, 85 participants took part in 14 focus groups between January and March 2021. Two major themes were identified, trust and personal and public benefits of sharing health information. The ability to exercise control over personal information, perceived transparency of the process, and the extent to which the healthcare service was viewed as confidential, all influenced the level of trust a person held. Perceived benefits were influenced by the extent to which participants believed information sharing would support improved care or provide broader public benefit, and balanced against the potential for personal harm. Conclusions: The findings allow for new insights into the views of the public on the use and sharing of personal health information and can be used to inform the development of a consent model for health information.