A Rh phosphine complex was encapsulated within the surface alkylated poly(propylene imine) dendrimers through ionic interactions. The resulting dendrimer complexes functioned as nanoreactors for hydroformylation of olefins. The congested surface of dendrimers with long alkyl chains favored hydroformylation of higher olefins. One-pot three reactions composed of hydroformylation, the Knoevenagel reaction, and hydrogenation proceeded within the dendritic nanoreactor.