Chiral metamaterials have attracted significant attention due to their unique optical properties, such as strong circular dichroism (CD) signals, which arise from the interaction between circularly polarized light and chiral structures. In this paper, we provide a three-dimensional chiral metamaterial platform with a stacked C-shaped unit cell for plasmonic excitation-based enhancement and tuning of the CD signals. Numerically, simulations of chiral metamaterials show that the strong CD response is displayed in the infrared light spectrum, where the greatest CD value is 85% at 1445 nm. There is also almost no transmission of right-circularly polarized light (RCP) in a width from 1340 to 1436 nm, which can serve as a circular dichroism filter. In order to identify the origin of the chiral signal, components’ coupling has been investigated using the linear superposition method. The CD response can be controlled by adjusting the period, the distance between two gold particles, and the thickness of the nanostructure. At the same time, we found that the maximum value of CD is increased to 93% when the thickness of the lowest layer particle is reduced to 50 nm. Our results provide a new approach for designing chiral metamaterials with tunable optical properties, which have potential applications in circularly polarized light filters and detectors.