A 5G communication system includes massive machine-type communication, enhanced mobile broadband, and ultra-reliable low-latency communication. To meet the requirements of 5G applications, researchers have considered various scalable subcarrier spacings and transmission time intervals. In this article, we introduce the concept of waveform multiplexing, which is a resource management system for numerology multiplexing that employs appropriate waveforms to various numerologies. It also possesses both a dynamic cyclic prefix and a minimum guard band, which are the key features for achieving high spectral efficiency. We verify the significant gain produced by proposed waveform multiplexing by performing extensive 3D ray-tracing- based system-level evaluations in realistic 3D environments. Finally, we provide guidelines on waveform multiplexing design by considering the time-domain and frequency-domain characteristics of the new radio waveform candidates.