Between 2008 and 2010, Glynn was Research Registrar at the National Breast Cancer Research Institute (NBCRI) in University College Hospital Galway.[2] Between 2010 and 2014, he was Senior House Officer and Specialist Registrar at the Health Service Executive (Otolaryngology).[2] Between 2014 and 2018, he was Specialist Registrar and Specialist in Public Health Medicine at the HSE.[2]
Glynn holds a diploma in personal leadership and executive coaching.[2] He has been a member of the Royal College of Surgeons in Ireland since 2012, a Fellow of the International Society for Quality in Healthcare (ISQUA) since 2013, and a Member of the Royal College of Physicians of Ireland (Faculty of Public Health Medicine), since 2017.[2]
Glynn was appointed Deputy Chief Medical Officer in October 2018.[2] He became a regular presence at the daily COVID-19 press conferences, along with the CMO, Dr Tony Holohan, and made multiple media appearances following the COVID-19 pandemic's emergence and its subsequent arrival in Ireland.[3][4] On 2 July 2020, Holohan made an announcement that he would be taking a hiatus from his position as Chief Medical Officer to care for his family as his wife entered palliative care with multiple myeloma; Glynn was subsequently appointed Acting Chief Medical Officer until 5 October 2020.
Aside from the frequent pandemic press conferences, he gave a televised interview to The Late Late Show on 4 September 2020.[5]
On 10 May 2022, the Department of Health announced that Glynn would resign at the end of the month to take up a role with consultancy firm EY which commenced in September.[6]