Senegal's Fatma Samba Diouf Samoura has been appointed as Fifa's first female secretary general.
She succeeds former secretary general Jerome Valcke, who was banned from football-related activity for 12 years.
Samoura, 54, spent 21 years working for the United Nations and will start at football's governing body in June.
"It is essential Fifa incorporates fresh perspectives as we continue to restore and rebuild our organisation," said Fifa president Gianni Infantino.
"She has a proven ability to build and lead teams, and improve the way organisations perform. Importantly for Fifa, she also understands that transparency and accountability are at the heart of any well-run and responsible organisation."
Samoura's appointment, announced at Fifa's congress in Mexico City, completes a new-look to an organisation which has been dogged by corruption allegations under Valcke and previous president Sepp Blatter.
Blatter, who had led Fifa since 1998, stood down last year and was later suspended from football for six years for breaching ethics guidelines.
On his appointment in February, Infantino said he would "work tirelessly to bring football back to Fifa and Fifa back to football".
Samoura, who will undergo an eligibility check before her role is ratified, currently works for the UN in Nigeria, and speaks four languages.
Samoura 'honoured' to take up new role
She started her UN career as a senior logistics officer with the World Food Programme in Rome in 1995 and has since served as country representative or director in six African countries, including Nigeria.
"Today is a wonderful day for me, and I am honoured to take on this role," she said.
"This role is a perfect fit for my skills and experience - strategic, high-impact team building in international settings - which I will use to help grow the game of football all over the world.
"I also look forward to bringing my experience in governance and compliance to bear on the important reform work that is already underway at Fifa.
"Fifa is taking a fresh approach to its work - and I am eager to play a role in making that approach as effective and lasting as possible."
BBC sports editor Dan Roan:
"For an organisation that has been accused in the past of being "blatantly sexist", the appointment of the first woman to such a senior position will be seen as a positive move.
"With new reforms limiting the powers of the Fifa president, Ms Samoura arguably becomes the most important figure in world football. Effectively the chief executive of the governing body, she will be in charge of the day-to-day running of the organisation as it attempts to recover from the corruption crisis that has threatened its very existence.
"With sponsors, campaigners and fans demanding more independence in the running of the sport, the arrival of a figure from outside football politics will also please some critics. A veteran of UN humanitarian programmes, it will be interesting to hear Ms Samoura's views on Qatar and concerns over the treatment of workers in the country as it prepares to host the 2022 World Cup.
"A Senegalese secretary general will also help FIfa's European president Gianni Infantino build bridges with Africa and other confederations, some of whom no doubt miss his predecessor Sepp Blatter."