In our efforts to develop effective treatment agents for human multiple myeloma (MM), a series of hybrid molecules based on the structures of thalidomide (1) and curcumin (2) were designed, synthesized, and biologically characterized in human multiple myeloma MM1S, RPMI8226, U266 cells, and human lung cancer A549 cells. The biological results showed that two hybrid compounds, 5 and 7, exhibited significantly improved lethal effects towards all three human MM cell models compared to 1 or 2 alone, as well as the combination of 1 and 2. Furthermore, mechanistic studies in U266 cells demonstrated that 5 and 7 can induce the production of reactive oxygen species (ROS) and cause G1/S arrest, thus leading to apoptosis and cell death. Additionally, they exhibited inhibitory effects on NFκB activation in A549 cells. Collectively, the results obtained from these hybrid compounds strongly encourage their further optimization as new leads to develop effective treatment agents for human MM.