Various types of photonic applications, such as sensing and communication, require the generation of wideband optical frequency-modulated (FM) signals. However, generating a wideband FM signal beyond the electrical bandwidth limitation of optical modulators is difficult. Here, we propose a method to increase the bandwidths of optical FM signals by using the cascaded four-wave-mixing (FWM) process and show its potential in two applications. We first demonstrate elevenfold bandwidth expansion of frequency-modulated continuous-wave (FMCW) signals (from 5 GHz to 55 GHz), beyond the optical modulator bandwidth. Next, we demonstrate signal-to-noise ratio (SNR) enhancement for analog communication. The SNR of an analog signal can be increased by approximately 12.8 dB using the proposed method. These results show the potential of the proposed method for sensing and communication applications. In addition, the proposed concept opens new possibilities in parametric FWM applications.