For the first time, a woman will command a UN peacekeeping force, after Norway's Major General Kristin Lund was appointed to lead troops in Cyprus.
Maj Gen Lund, 55, has a distinguished military career going back 34 years and including postings in Lebanon and Afghanistan, a UN statement said.
She will replace China's Major General Chao Liu on 13 August.
In Cyprus, she will command 996 soldiers and police officers as well as 149 civilian staff.
The island has been divided since 1974 when Turkey invaded the north in response to a military coup on the island which was backed by the government of Greece.
Since then, the northern third has been mainly inhabited by Turkish Cypriots and the southern two-thirds by Greek Cypriots.
Message to women
Maj Gen Lund was congratulated on her appointment by UN Secretary General Ban Ki-moon at UN headquarters in New York.
Interviewed by the Associated Press news agency, she said she was looking forward to the challenges of her new job - maintaining the ceasefire and supporting efforts to deal with minefields, unaccounted people, property disputes and other issues.
She also said she was proud to crack the glass ceiling in UN peacekeeping: "I think it's time, and I think it's important, that other women see that it's possible also in the UN system to get up in the military hierarchy to become a force commander."
Her first overseas mission was in 1986 as transport officer with the UN peacekeeping mission in Lebanon.
That, she said, was where fell in love with the UN and learned that "maybe the most important weapon that you have is communication and to build relations".