<p>The increasing demand for energy-efficient and sustainable building materials has driven the growth of cross-laminated timber (CLT) in heavy timber construction. However, the flammability of wood remains a key challenge. This study compares the combustion characteristics of laminated bamboo lumber (LBL) and spruce–pine–fir (SPF) in bamboo–wood composite (BWC) CLT panels. Using a cone calorimeter, the combustion parameters of both materials were measured, and the effects of heat flux were analyzed. Fire furnace experiments were also conducted to evaluate the charring rate, fire performance, and structural integrity of the panels under standard fire conditions. Results show that LBL exhibits superior fire performance compared to SPF upon ignition, but its peak heat release rate during secondary combustion is more intense, indicating a higher thermal hazard. However, LBL maintains its structural integrity longer after combustion and produces lower emissions of CO and CO₂, reducing health risks. The charring rate of BWC CLT is higher than that of SPF, but it meets fire resistance limits exceeding 1.5 h. This performance, coupled with the unique fiber arrangement of bamboo and slow combustion rate, highlights its potential in enhancing fire safety. The findings contribute to the optimization of CLT design for improved fire performance, supporting sustainable development in fire-resistant timber construction.</p>