The Ireland East Branch is the Institution's 37th branch across the world and replaces the IOSH Ireland Branch's Eastern District.
Around 700 IOSH members based in counties including Louth, Meath, Dublin, Kildare and Wicklow are now part of the new branch.
The launch event is being held in the Health and Safety Authority Offices in James Joyce Street, Dublin, between 5pm and 8pm on Wednesday 27 January.
Branch chair Yvette Moffatt will give an introductory presentation. Ahead of the event, she said: "It makes perfect sense to make this change. Having the biggest membership in Ireland gives us the strength to move forward to the next level.
"We plan to develop more opportunities for our members to get involved. Most importantly we plan to help and support our members who are going through the IPD process and provide continuing support to those who are pursuing their CPD."
The event will also see presentations from Matt Rockley, IOSH's Regional Networks Manager for UK and Ireland, and Michael Gillen from the Health and Safety Authority.
The new branch will also work to liaise with employers and employer groups to recognise the importance of the safety and health professional in their organisation, Yvette added.
The switch to branch status coincides with the 20th anniversary of the formation of the IOSH Ireland Branch's Eastern District.