Background: A primary brain cancer diagnosis is a distressing, life changing event. It adversely affects the quality of life for the person living with brain cancer and their families (‘carers’). Timely access to evidence-based information is critical to enabling people living with brain cancer, and their carers, to self-manage the devastating impacts of this disease. Method: A systematic environmental scan of web-based resources. A depersonalised search for online English-language resources published from 2009 to December 2019 and designed for adults (> 25 years of age), living with primary brain cancer, was undertaken using the Google search engine. The online information was classified according to: 1) the step on the cancer care continuum; 2) self-management domains (PRISMS taxonomy); 3) basic information disclosure (Silberg criteria); 4) independent quality verification (HonCode); 5) reliability of disease and treatment information (DISCERN Sections 1 and 2); and readability (Flesch-Kincaid reading grade). Results: A total of 119 online resources were identified, most originating in England (n = 49); Australia (n = 27); or the USA (n = 27). The majority of resources related to active treatment (n = 76), without addressing recurrence (n = 3), survivorship (n = 1) or palliative care needs (n = 13). Few online resources directly provided self-management advice for adults living with brain cancer or their carers. Just over a fifth (n = 26, 22%) were underpinned by verifiable evidence. Only one quarter of organisations producing resources were HonCode certified (n = 9, 24%). The median resource reliability as measured by Section 1, DISCERN tool, was 56%. A median of 8.8 years of education was required to understand these online resources. Conclusions: More targeted online information is needed to provide people affected by brain cancer with practical self-management advice. Resources need to better address patient and carer needs related to: rehabilitation, managing behavioural changes, survivorship and living with uncertainty; recurrence; and transition to palliative care. Developing online resources that don’t require a high level of literacy and/or cognition are also required.