This paper focuses on fracture toughness measured using end‐notched flexure tests under Mode II static loading in aluminium alloy (5052‐H34), glass fibre‐reinforced polypropylene matrix composite (GF/PP) and carbon fibre‐reinforced epoxy matrix composite (CF/EP) adherends bonded with DP8005 adhesive. Traction–separation relations are also presented using a cohesive zone model to estimate the fracture toughness under mixed‐mode loading. The experimental results show that the fracture toughness values of the aluminium alloy, GF/PP and CF/EP specimens are 2398, 2474 and 2428 Jm−2, respectively. Fracture surface observations reveal that failure types for the aluminium alloy, GF/PP and CF/EP specimens are mainly cohesive. It can be concluded that Mode II fracture toughness shows a low degree of dependence on the different adherends bonded with an acrylic‐based adhesive when cohesive failures are dominant. By assigning the experimental parameters in the failure criteria, the fracture toughness can be estimated under different mixed modal ratios.