In this research the thermal, crystallization, and mechanical properties of branched poly (butylene succinate) (PBS) copolymers, which were synthesized through a two-stage esterification and condensation polymerization from 1,4-butanediol, 1,2-decanediol, and succinic acid and abbreviated as PBDS, were systematically investigated and compared with those of PBS homopolymer. Both PBS and PBDS copolymers showed relatively high and similar molecular weights, with the weight average molecular weights of 6.89 × 104 g/mol and above. PBDS copolymers showed the similar high thermal stability as PBS. With an increase in 1,2-decene succinate (DS) content, the glass transition temperature, melting point temperature, and equilibrium melting point temperature of PBDS copolymers gradually decreased. At the same cooling rate, the melt crystallization temperature of PBDS copolymers decreased, while at the same degree of supercooling, the crystallization half-time increased. The branching did not modify the crystallization mechanism and crystal structure of PBDS copolymers. Both the storage modulus and the glass transition temperature of PBDS copolymers gradually decreased with increasing the DS content. Compared with PBS, increasing the DS content obviously improved the elongation at break and accordingly decreased the Young's modulus and tensile strength of PBDS copolymers. In brief, the thermal, crystallization, and mechanical properties of PBS may be conveniently tuned by a copolymerization method via the introduction of branching. Display omitted •The thermal, crystallization and mechanical properties of branched PBS were studied.•With increasing DS content, the Tg, Tm and Tmo of PBDS copolymers decreased.•The crystallization of PBDS copolymers significantly was retarded by the branching.•The branching did not modify the crystallization mechanism and crystal structure.•The dynamic and tensile mechanical properties were clearly affected by the branching.