The diagnosis of childhood cancer not only affects the life of the child but also impacts the lives of the caregivers as well. This study aims to explore the caregiving stress, coping strategies, and support needs of mothers caring for children/adolescents with cancer during the active treatment phase. Individual semi-structured interviews were conducted, and two authors independently and thematically analyzed data. Caregiving mothers went through a process of emotional changes and a change in lifestyles when their children were diagnosed with cancer and undergoing treatments. It is important to ensure that caregiving mothers of children/adolescents with cancer are well supported by family, friends, and healthcare professionals. Healthcare professionals can develop informational booklets on cancer treatment protocols and work together with mothers. Parent support groups and plans for psychoeducational and spiritual care programs for mothers as forms of informational and emotional support may also be established.