The structural performance of engineered timber products depends strongly on the behavior of bonded interfaces. This study investigates Mode I fracture of Chilean Pinus radiata D. Don bonded with a one-component polyurethane (1C-PUR) adhesive through Double Cantilever Beam (DCB) tests in the tangential–longitudinal (TL) and radial–longitudinal (RL) planes. Two predominant crack propagation paths, adhesive-dominated (AD) and timber-dominated (TD), were identified by visual inspection of the fracture surfaces, and the results were compared with previously reported solid timber (ST). Equivalent R-curves were obtained from specimen compliance without direct crack-front tracking, and trilinear cohesive laws were identified through dimensional analysis. TD specimens exhibited higher mean critical strain energy release rates (G_Ic) than AD specimens, with 535.56 and 428.05 [N/m] in TL and RL, respectively, compared with 338.92 and 274.04 [N/m]. Relative to ST, the mean G_Ic was 105% and 75% higher for TD and 30% and 12% higher for AD, although the RL-AD difference was small compared with its variability. The critical opening displacement of the bonded specimens was less than half that of ST, whereas the cohesive tensile strength was only weakly identifiable and is reported as an effective parameter. The results provide a basis for simulating bonded laminated and cross-laminated timber structures.