Abstract: To elucidate the influence of aged vinegar on the flavor development of fish-flavor seasoning sauce, this study systematically investigated the differences in volatile compounds among samples prepared with vinegars aged for 1, 3, and 5 years. Advanced analytical techniques, including electronic nose (E-nose), headspace–gas chromatography–mass spectrometry (HS-GC-MS), odor activity value (OAV), and orthogonal partial least squares discriminant analysis (OPLS-DA), were employed. The E-nose and principal component analysis (PCA) revealed that the D sample (5-year-aged vinegar) exhibited the most distinct odor profile compared to the control (A, without vinegar), while samples B (1-year) and C (3-year) showed high similarity. This trend was further validated by cluster heatmap and PCA of key aroma substances, indicating that aged vinegar significantly altered the overall odor composition. A total of 76 volatile compounds were identified by GC-MS, with aldehydes, esters, terpenes, and sulfur-containing compounds as the major components. With increasing vinegar age, the contents of aldehydes and esters increased, whereas those of terpenes and sulfur compounds decreased. OAV analysis identified 40 aroma-active compounds, among which (E)-2-heptenal, nonanal, dodecanal, trans-2,4-decadienal, isovaleraldehyde, and diallyl tetrasulfide were the most prominent contributors to the characteristic flavor. The OPLS-DA model highlighted 12 marker compounds with a variable importance in projection (VIP) greater than 1, such as valeraldehyde and 4-ethylphenol, as key discriminants among the samples. This study reveals the regulatory role of aged vinegar in shaping the key aroma-active profile of fish-flavor seasoning sauce, providing a theoretical foundation for the standardization and quality enhancement of compound condiments.