A palladium-catalyzed multicomponent method for the synthesis of β-lactams from imines, aryl halides, and CO has been developed. This transformation proceeds via two tandem catalytic carbonylation reactions mediated by Pd(PtBu3)2 and provides a route to prepare these products from five separate reagents. A diverse range of polysubstituted β-lactams can be generated by systematic variation of the substrates. This methodology can also be extended to the use of iodo-substituted imines to produce novel spirocyclic β-lactams in good yields and selectivity.