Abstract Background Identification and prevention of mobility limitations in older adults is important to reduce adverse health outcomes. The Life-Space Assessment (LSA) provides a single measure of mobility including environmental and social resources of the older adult. Availability of the LSA for non-English speaking countries is still sparse. Therefore, we translated the LSA into Danish and performed a content validity analysis of the translation in older adults with mobility limitations. Methods After translation into Danish, the Danish version (LSA-DK) was content validated using cognitive interviewing in older mobility limited adults (+ 65) from an outpatient rehabilitation center (n = 12), medical wards at a university hospital (n = 11), and an assisted living facility (n = 7). The interviews were transcribed and analyzed according to the four stages of the Information Processing Model. Based on the analyses, recommendations for changes to the LSA-DK and to the manual were made and presented to the developers of the LSA. Results Consensus was reached on the LSA-DK. Thirty cognitive interviews were carried out. A wide range of sources of error primarily related to the comprehension, memory and decision process were identified. The frequency and type of error sources were most prevalent among assisted living facility informants and included difficulties in defining the geographical extension of neighborhood, town and outside town. The results led to adaptations to the questionnaire and manual to support implementation of the LSA-DK in clinical practice. Conclusions The Life-Space Assessment was translated into Danish and content validated based on cognitive interviews. Adaptations were made to support that the Danish version can be implemented in clinical practice and used in the assessment of mobility in older Danish adults.