Adipose tissue is continuously regenerated by stromal mesenchymal stem cells throughout life. This study hypothesises that early age-related changes in the proteome and metabolic properties of subcutaneous (s) and visceral (v) adipose tissue-derived stromal/stem cells (ASCs) from young and old rabbits contribute to a loss of stem cell plasticity and function. To test this, the proteome and metabolic properties of ASCs from young and old rabbits were analysed using mass spectrometry-based label-free quantification and mitochondrial respiration measurements (Seahorse Mito Cell Stress Test). Both sASCs and vASCs from old rabbits exhibited comparable clusters of differentially expressed proteins. However, age-related changes were more pronounced in sASCs, suggesting that ageing affects ASCs differently depending on anatomical origin. In particular, a cluster of mitochondrial proteins in sASCs was differentially expressed with age, correlating with a shift in metabolic profile. The increase in mitochondrial respiration indicates that ageing ASCs lose their quiescent state and plasticity, leading to accelerated proliferation and differentiation. These proteomic findings were validated by Western Blot analysis, which confirmed the differential expression of key mitochondrial proteins. These results highlight the role of cellular origin in stem cell ageing and provide insights into the mechanisms underlying age-related stem cell dysfunction.