<p>This study presents the first investigation of <i>Achillea ligustica</i> in Tunisia, examining the chemical composition and biological activities of extracts and essential oils from two distinct populations. Extracts were obtained from inflorescences, combined stems and leaves, and roots using solvents of varying polarity. Essential oils were extracted from the inflorescences and combined stems and leaves. Gas chromatography–mass spectrometry (GC–MS) analysis of the essential oils identified 44 terpenes, with chrysanthenone (8.02–21.09%), terpinene 4-ol (4.32–16.29%), artemisia ketone (6.9–15.81%) and camphor (6.31–10.57%) as the most abundant components. Principal Component Analysis (PCA) revealed distinct groupings of major compounds based on organ type and geographical origin. The polyphenol, flavonoid, and flavonol contents of the extracts were determined. Inflorescence extracts from Babbouch exhibited the highest polyphenol and flavonoid contents, while the combined stems and leaves extract from Babbouch showed the highest flavonol content. Antioxidant activity of the essential oils and extracts was evaluated using DPPH and ABTS assays. The essential oil from the combined stems and leaves of Feija demonstrated the highest activity in both assays correlating with specific terpenic compounds including camphene and linalool. Among the extracts, ethanolic extracts from Babbouch displayed the highest radical scavenging activities, with the combined stems and leaves showing the best anti-DPPH activity and inflorescences the best anti-ABTS activity. Significant correlations were observed between ABTS radical scavenging activity and phenolic contents. This study highlights the antioxidant properties of <i>A. ligustica</i>, likely attributed to its rich phenolic and bioactive terpenic compound content, suggesting its potential as a valuable natural resource for industrial applications.</p> Graphical Abstract <p></p>