Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) was blended with poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) to improve physical properties and biocompatibility of PHBHHx for a wide range of biomedical applications. PHBHHx was completely miscible with P3HB4HB in their blends. All the PHBHHx/P3HB4HB blends showed improved physical properties compared with PHBHHx, including higher thermal stability, flexibility and mechanical strength. All the blends had more hydrophilic surface, higher polar component and rougher surface than PHBHHx. The PHBHHx/P3HB4HB blend in 4:2 weight ratio showed the roughest surface and also had the highest chondrocyte viability among all the blends and the polymers tested, which was 59% higher than that on PHBHHx and 32% higher than that on P3HB4HB. The blend with 4:2 weight ratio also had the maximum cartilage-specific collagen II mRNA expression among all the blends and the polymers tested, which was 9-times higher than that on PHBHHx and 8-times higher than that on P3HB4HB. These results demonstrated that PHBHHx had improved physical properties and biocompatibility after blending with P3HB4HB. The blends could be used for cartilage tissue engineering.