We experimentally demonstrate C-band direct-detection (DD) power division non-orthogonal multiple access (PD-NOMA) aided wavelength-division multiplexed (WDM) data transmission over 50-km distance [standard single-mode fiber (SSMF) + non-zero dispersion-shifted fiber (NZDSF)] for far user at 10-Gbps data rate. For 5-Gbps data rate, a distance of 100 km is achieved for far user. The transmission system is made of mixed fiber types to include both linear and nonlinear fiber impairments. We have utilized successive interference cancellation technique assisted by K-means clustering algorithm for the detection of the multi-user 3  ×  20 Gbps on–off keying modulated WDM PD-NOMA signal. The obtained results reveal that the unsupervised K-means clustering-based DD receiver provides 7% hard decision- forward error correction BER limit of 3.8  ×  ^{10  −  3} for all three channels for both 100-/50-GHz channel spacing and 5-/10-Gbps data rates. For the case of a single-channel-based system, the BER well below the pre-FEC limit is achievable for both the data rates of 5 and 10 Gbps even after 50 km (for 10 G)/100 km (for 5 G) SSMF/SSMF + NZDSF for far user. Using the K-means algorithm, the maximum power penalty for the 10-Gbps single channel and WDM channels are 5 and 6.6 dB, respectively. The proposed detection technique is able to detect the data even for the far user at a distance of 100 km. Most significantly, no compensation techniques have been utilized for the fiber impairments in the proposed system.