Background <p>Multimorbidity and chronic disease burden are common among older patients and are closely associated with frailty, poor sleep, and reduced subjective well-being. However, total-score-based analyses may obscure item-level interactions across health domains. This study examined the network structure of frailty, sleep quality, and life satisfaction in older patients and explored whether association patterns varied across chronic disease burden levels.</p> Methods <p>This cross-sectional study included 1,107 older patients. Multimorbidity was defined as the presence of two or more chronic diseases. Frailty, sleep quality, and life satisfaction were assessed using the Fatigue, Resistance, Ambulation, Illnesses, and Loss of Weight (FRAIL) scale, Pittsburgh Sleep Quality Index (PSQI), and Satisfaction With Life Scale (SWLS), respectively. A regularized partial correlation network was estimated using the graphical least absolute shrinkage and selection operator (LASSO) with extended Bayesian information criterion (EBIC) model selection (EBICglasso), with scale items or components as nodes. Strength, expected influence, and bridge centrality were calculated. Stratified analyses were conducted by number of chronic diseases, and bootstrap procedures were used to assess network accuracy and stability.</p> Results <p>Multimorbidity was present in 1,078 participants (97.4%), and the median number of chronic diseases was 5 (IQR, 3–6). Network analysis showed that SWLS-related nodes had relatively high strength and bridge strength, indicating relatively high statistical connectivity within the overall network and across communities. Sleep-related nodes, particularly sleep latency, use of sleeping medication, and daytime dysfunction, were prominent in signed centrality indices. Frailty nodes were mainly connected to SWLS nodes through negative edges. The SWLS community showed dense internal connections, whereas frailty and sleep quality were linked to life satisfaction primarily through negative cross-community edges. In descriptive stratified analyses, negative cross-community connections appeared more pronounced in the group with ≥ 5 chronic diseases. Because the cutoff was data-driven and no formal network comparison test was performed, the apparent between-group differences should be interpreted as descriptive and exploratory rather than statistically confirmed. Network stability analyses indicated acceptable stability.</p> Conclusions <p>Among older patients, life satisfaction-related nodes showed relatively high overall connectivity, while several sleep-related nodes showed notable statistical associations within the estimated network. Given the high prevalence of multimorbidity in this sample, multidisciplinary assessment and health management should consider the interrelations among sleep problems, frailty, and life satisfaction in the context of chronic disease burden. Network analysis may provide exploratory evidence on cross-domain associations in complex health problems among older patients, but apparent differences across chronic disease burden groups require confirmation using formal network comparison tests and longitudinal designs.</p>