Koirala was the first child of the colonel Pratap Singh Gurung and Laxmi Devi Gurung. She belonged to an educated family and was educated at St Joseph Convent School. Before she started Maiti-Nepal, she spent 20 years as a teacher, teaching English in different schools in Kathmandu.
Maiti Nepal operates a rehabilitation home in Kathmandu, as well as transit homes at the Indo-Nepal border towns, preventive homes in the countryside, and an academy in Kathmandu. Maiti Nepal ("Maiti" means "mother's home" in Nepali) has been a refuge for women rescued from the brothels in India. The women can stay in the homes run by Maiti Nepal until they can return to their homes, or if not accepted by their parents and society, they may stay until they become able to live independently. Between 1993 and 2022, she and her organisation have helped rescue and rehabilitate more than 50,000 women and girls.
Maiti Nepal also works on reuniting the rescued women with their families, patrolling the Indo-Nepal border with police and other law enforcement authorities, and also rescuing trafficked women from brothels in India with the help of Indian authorities.[4]
Koirala received the Best Social Worker of the Year Award (Nepal) in 1998, the Prabal Gorkha Dakshin Bahu Medal (Nepal) in 1999, the Trishaktipatta Award in 2002, the Courage of Conscience Award from The Peace Abbey Foundation in 2006, German UNIFEM Prize in 2007 and Queen Sofia Silver Medal Award in 2007.