Mamello is a nurse midwife who works in the rural areas of Lesotho to promote maternal health and well being. She has assuled various leadership positions both internationally and locally. She is the Co-founder of Barali foundation. SheDecides global young leader and United Nations Major Group for children and youth focal point. She has participated in numerous maternal health platforms such as the International conference of population developemnt () (ICPD25) kenya, Women Deliver conference Canada, TICAD IV Japan, SheDecides flagship day Nepal, and African convening Kemya. Her work entails advoacting for safe medical abortion, accessibility of family planning contraception, advoacte for laws eradicating gender inequalities and end all forms of violence and discrimination against women, within national development agendas including engaging in the formulation of national plans.