In 2009, she completed a master's degree in public administration and international law at Columbia University in New York. She was a Fulbright scholar. After graduating with her bachelor's degree in 2004, Rahmani returned to Afghanistan and worked for several Canadian nonprofits focusing on human rights, women’s empowerment, and education. She also worked part-time as a subject matter expert with the NATO Joint Forces Training Center, and a consultant to the New York Department of Education, the United Nations Secretariat in New York, the Department of Trade and International Affairs of Canada, Canadian Women for Women in Afghanistan, Women Living under Muslim Laws, and other INGOs. During this time Rahmani worked on a marriage document that secured equitable rights for the family and contributed to data collection at a national level. She received the Best Human Rights Activist Award from the Afghanistan Independent Human Rights Commission in 2007 for her work on this document. Rahmani joined the Afghan government, first in the Ministry of Education, then as a Senior Advisor to the Deputy Foreign Minister in 2011. From 2012-2016, she served as the Ministry of Foreign Affairs Director General for Regional Cooperation. In this role she initiated and promoted important regional cooperation initiatives, like the Heart of Asia-Istanbul Process. From June 2016-December 2018, Rahmani served as Afghanistan's first female ambassador to Indonesia, non-resident ambassador to Singapore, and first ever ambassador to the Association of Southeast Asian Nations. She was the second woman appointed as an ambassador by President Ashraf Ghani, after he vowed to give women more leadership positions. She said Muslim women could introduce a narrative of a "dynamic Muslim", proving that religion is not a static force. On 14 December 2018, Rahmani was appointed Ambassador to the United States by President Ghani, the first woman to hold the position. She took up the post just as President Trump announced his intention to withdraw troops from her country. She said, "women have been treated like a minority, but they are not a minority. Together, the women and the youth are actually a majority, and they are not willing to give up their rights. They are not willing to compromise their human rights and go back to the old days." She replaced Hamdullah Mohib, who had resigned three months earlier to become National Security Advisor. Ambassador Rahmani also serves as Afghanistan's non-resident ambassador to Mexico, Argentina, Colombia, and the Dominican Republic. Rahmani spent several years working at nonprofits that focused on women's rights and education. At this time, her work focused particularly on family law reform in the Muslim context.