(1) Objective: To identify the assessment tools and outcome measures used to assess older adults for inpatient rehabilitation. (2) Design: Scoping review. (3) Data sources: ProQuest, PEDro, PubMed, CINAHL Plus with full text (EBSCO), Cochrane Library and reference lists from included studies. (4) Review method: The inclusion of studies covering patients aged >60, focusing on rehabilitation assessments delivered in hospitals in community settings. Studies reporting on rehabilitation specifically designed for older adults—testing for at least one domain that affects rehabilitation or assessments for admission to inpatient rehabilitation—were also included. Results were described both quantitatively and narratively. (5) Results: 1404 articles were identified through selected databases and registers, and these articles underwent a filtering process intended to identify and remove any duplicates. This process reduced the number to 1186 articles. These, in turn, were screened for inclusion criteria, as a result of which 37 articles were included in the final review. The majority of assessments for geriatric rehabilitation were carried out by a multidisciplinary team. Multiple studies considered more than one domain during assessment, with a high percentage evaluating a specific outcome measure used in geriatric rehabilitation. The most common domains assessed were function, cognition and medical status—with communication, vision and pain being the least common. A total of 172 outcome measures were identified in this review, with MMSE, BI, FIM and CCI being the most frequent. (6) Conclusions: This review highlights the lack of standardised approaches in existing assessment processes. Generally, older-adult-rehabilitation assessments struggle to capture rehabilitation potential in a holistic manner. Hence, a predictive model of rehabilitation for assessing patients at the initial stages would be useful in planning a patient-specific programme aimed at maximising functional independence and, thus, quality of life.