Background <p>Sarcopenia, characterised by ageing-related loss of muscle mass and strength, is a major contributor to functional decline and increased fall risk in older adults. As postural stability is essential for mobility and autonomy, the interplay between sarcopenia and balance disorders has become a critical area of investigation. While clinical assessments such as the Berg Balance Scale and Timed Up and Go test suggest that sarcopenia impairs balance, these tools may not capture subtle postural deficits. Stabilometric analysis offers a more objective and detailed evaluation, yet current research lacks representation of the oldest and frailest populations. This study aims to examine the distinct impact of sarcopenia to postural instability in individuals aged over 75, using stabilometric analysis.</p> Methods <p>This retrospective, observational, single-centre case–control study was conducted in a university hospital day clinic between January 2021 and February 2023. Medical records of 354 patients aged ≥ 75&#xa0;years were analysed, including 235 non-sarcopenic and 119 probable sarcopenic individuals, classified per EWGSOP2 criteria. All participants underwent standardised geriatric, nutritional, and functional evaluations. Postural stability was assessed using a force platform under four visual and surface conditions. Centre of Pressure (CoP) parameters, length, mean velocity, displacement amplitude, and sway area, were measured. ANCOVA analyses controlled for confounders including age, sex, frailty status, malnutrition, BMI, and fall history.</p> Results <p>Sarcopenic patients were older, frailer, and exhibited significantly reduced functional performance across all tests. Stabilometric analysis revealed increased Cop length, mean velocity, and displacement amplitudes in sarcopenic individuals under all conditions (<i>p</i> &lt; 0.0001), except for CoP surface area on unstable ground with eyes open. ANCOVA confirmed that these associations remained significant after adjustment for relevant covariates: age, sex, frailty status, malnutrition, BMI, and fall history. The impact was particularly pronounced under challenging conditions, such as unstable surfaces and visual deprivation.</p> Conclusions <p>Sarcopenia is a dominant and independent determinant of postural instability in individuals over 75&#xa0;years old. It significantly alters stabilometric parameters, indicating impaired neuromuscular and sensorimotor control. These findings highlight the limitations of traditional clinical assessments and support the integration of stabilometric testing into geriatric evaluations.</p>