In this study, we aimed to investigate the benefits of co-design prompts/aids in the development of assistive devices for and with older adults who have cognitive impairment (CI), with the goal of improving their ability to live independently at home. We conducted a series of co-design workshops and utilized eight sets of multi-sensory aids to explore their values and effectiveness in engaging older adults with CI in co-design processes. Our findings revealed that the co-design aids had several benefits, including: (1) increasing the exchange of knowledge and awareness between older adults and designers; (2) eliciting insightful information through multi-sensorial aids, and (3) generating novel assistive design solutions to support seniors’ independent living at home. We discuss our findings in relation to the multi-sensorial attributes of co-design aids, which empower older adults with CI to express their opinions and actively participate in co-designing assistive devices that meet their needs/expectations.