Chemical composition and antioxidant activity of four aniseed populations (Egyptian, Serbian, Tunisian and Turkish) were investigated during three developmental stages. The highest oil yield was achieved at full maturity in all aniseed accessions ranged from 11.93% (Serbia) to 13.80% (Tunisia). Fatty acid profile of aniseed oil was characterized by high proportions of palmitic (4.90–57.18%) and petroselinic (10.48–46.60%) acids which had an antagonist evolution during maturation. The essential oil yield reached its maximum at the beginning of ripening process in all aniseed accessions ranged from 1.94% (Serbia) to 3.09% (Tunisia). The main essential oil compound was trans-anethole (66.34–93.05%) during aniseed ripening in all accessions. Phenolic content patronized its maximum at the last stage of aniseed ripening ranged from 17.11 mg GAE/g DW (Serbia) to 25.16 mg GAE/g DW (Tunisia). The main phenolic compound of aniseed was naringin (17.55–32.49%) and its accumulation was followed by the reduction of gallic, rosmarinic, ellargic and syringic acids during aniseed ripening in all accessions. Concerning antioxidant activity, DPPH scavenging activity, chelating ability and reducing power were maximal at full maturity in all aniseed accessions. Our findings indicate that the determination of optimal periods and provenances for antioxidant accumulation can be used to evaluate the quality of aniseeds and could be important for industries.