This systematic literature review studies and summarizes findings of requirements documentation of non-functional requirements practiced by agile software development teams. It identifies current practices and existing gaps when agile software teams discuss and implement non-functional requirements, and the current methods used to document non-functional requirements. Our aim is to identify available evidence on current practices and gaps in documenting non-functional requirements. The review was conducted by searching major databases for publications between 2018 and 2022. The inclusion and exclusion criteria as well as quality assessment scoring criteria were subsequently established. Results show that common themes in the practices and gaps in requirements documentation by agile teams do intersect although they are scarce. This review has the benefit for practitioners to have a better approach to document the requirements that may result in a more quality software product.