The Department of Health has confirmed that Chief Medical Officer Dr Tony Holohan will return to work next Monday, 5 October.
He took temporary leave in July to deal with personal family circumstances.
Dr Ronan Glynn has been Acting Chief Medical Officer since Dr Holohan stepped aside.
Dr Holohan said that he was "taking time out" from his work commitments to be with his family.
His wife Emer, who has a form of blood cancer, has been admitted to palliative care.
Dr Holohan said he said he wanted to give his "energy, attention and all of my time" to his wife and their teenage children.
The Taoiseach has thanked Dr Ronan Glynn for his "extraordinary service, dedication and honesty" over last few months in his role as acting Chief Medical Officer.
In a tweet this afternoon, Micheál Martin said as Dr Tony Holohan prepares to return to his post, he wanted to thank Dr Glynn for his work.
As Dr Tony Holohan @CMOIreland prepares to return to post, I want to thank Dr @ronan_glynn for his extraordinary service, dedication and honesty over last few months as Acting CMO. He's been a pleasure to work with, in some difficult circumstances, making v difficult decisions.— Micheál Martin (@MichealMartinTD) October 1, 2020