This study utilized calcined construction spoil from Guangdong as a partial replacement for cement in the preparation of green ultra-high-performance concrete (UHPC). The effects of different calcined construction spoil content levels (0%, 5%, 10%, 15%, and 20%) on the workability, mechanical property, and shrinkage behavior of UHPC were investigated. Additionally, a life cycle assessment (LCA) was performed to quantify carbon emissions. The results indicate that the incorporation of calcined construction spoil improves the fluidity of the UHPC mixture. At the age of 3 days, the effect of calcined construction spoil on the mechanical properties of UHPC is limited. However, at 7 and 28 days, the compressive strength and flexural strength of UHPC show a trend of initially increasing and then decreasing with the increase in calcined construction spoil content, reaching maximum values of approximately 172.5 and 32.7 MPa at a 10% replacement level, respectively. The use of calcined construction spoil reduces the shrinkage of the UHPC matrix, particularly the autogenous shrinkage. Within the range of dosages studied, the partial replacement of cement with calcined construction spoil can reduce the carbon emissions of UHPC by approximately 11.3%.