President Mahama said this when he commissioned Mrs Martha Ama Akyaa Pobee, Ambassador designate and permanent representative of Ghana to the United Nations.
Mrs Pobee, a Career Diplomat, replaces Mr Ken Kanda who is on retirement now.
The new UN permanent representative who took the oaths of office, allegiance and secrecy has been in the Foreign Service for 25 years and also acted as the Ambassador of South Africa.
She is the first female Ghana's Permanent representative to the United Nations.
President Mahama said she distinguished herself as the acting High Commissioner of South Africa and expressed the hope that she would do well in her new position in New York.
He said the UN is a busy schedule and urged her to perform her duties diligently to raise high the flag of Ghana and Africa during her duty tour of the country and organization.
Mrs Pobee expressed gratitude to President Mahama for the appointment and gave the assurance that she would perform to justify the confidence reposed in her.
"I will not disappoint... and I will make sure that I raise the Ghana flag high and undertake my duties responsibly."