Centrica executive Catherine O'Kelly will replace Dave Kirwan at the helm of Bord Gáis Energy.
Mr Kirwan is leaving the Irish utility to become managing director of customer operations at its UK parent, Centrica.
Bord Gáis Energy staff were told on Wednesday that Ms O’Kelly will replace Mr Kirwan as managing director from next September.
Ms O’Kelly has been chief of staff and director of industry development at Centrica UK. She led a number of key changes such as the introduction of smart meters.
She holds a degree in Politics, Philosophy and Economics from Oxford University and is a non-executive board member of the not-for-profit Peabody Community Foundation in the UK.
The group has appointed Mark Prentice as acting manging director until Ms O'Kelly takes up the new role in September.
Bord Gáis Energy supplies natural gas and electricity to consumers and businesses around the Republic.
Centrica bought the former Irish State company three years ago.