Cross laminated timber (CLT) is becoming increasingly popular for constructing multiple-story buildings due to its alignment with Sustainable Development Goals of United Nations. However, such structures can be susceptible to excessive vibrations during earthquakes. While tuned mass dampers (TMDs) can be used to control these vibrations in CLT structures, their effectiveness can be reduced due to the lightweight nature of CLT and changes in its structural mass or deterioration of the wood. To address this issue, this paper proposes the use of shape memory alloy-based semi-active tuned mass dampers (SMA-STMDs) for controlling vibrations in CLT structures. This study includes the design and experimental testing of a full-scale, novel spring-pendulum combined SMA-STMD system, which utilises the mechanical properties of SMAs that change with temperature to achieve semi-active control. Finite element method simulations demonstrate that the proposed SMA-STMD system can effectively reduce structural seismic vibrations in CLT structure. By adjusting the SMA temperature, the SMA-STMD system can effectively address the issue of TMD system off-tuning caused by changes in the CLT structural properties. Overall, the proposed SMA-STMD system offers a promising solution for seismic control in CLT structures and has the potential to promote the development of CLT structures.