The authors propose a novel method to probe primordial non-Gaussianities (NGs) by observing gravitational waves (GWs) induced by ultra-light primordial black holes (PBHs) with masses less than \(10^9\) grams. They argue that the existence of primordial NGs can leave imprints on the clustering properties of PBHs and the spectral shape of induced GW signals. Specifically, they identify a distinct double-peaked GW energy spectrum that may fall within the frequency bands of upcoming GW observatories such as LISA, ET, SKA, and BBO. By combining bounds on the GW amplitude from Big Bang Nucleosynthesis (BBN), they set a joint upper limit on the product of the effective nonlinearity parameter for the primordial trispectrum and the primordial curvature perturbation power spectrum. This limit is given by \(\tau_{\text{NL}} \mathcal{P}_R(k) < 4 \times 10^{-20} \Omega_{\text{PBH}, \text{f}} ( \frac{M_{\text{PBH}}}{10^9 \text{g}} )^{-17/9}\). The study highlights the potential of using GW signals from ultra-light PBHs to probe primordial NGs, providing a new tool for cosmological observations.The authors propose a novel method to probe primordial non-Gaussianities (NGs) by observing gravitational waves (GWs) induced by ultra-light primordial black holes (PBHs) with masses less than \(10^9\) grams. They argue that the existence of primordial NGs can leave imprints on the clustering properties of PBHs and the spectral shape of induced GW signals. Specifically, they identify a distinct double-peaked GW energy spectrum that may fall within the frequency bands of upcoming GW observatories such as LISA, ET, SKA, and BBO. By combining bounds on the GW amplitude from Big Bang Nucleosynthesis (BBN), they set a joint upper limit on the product of the effective nonlinearity parameter for the primordial trispectrum and the primordial curvature perturbation power spectrum. This limit is given by \(\tau_{\text{NL}} \mathcal{P}_R(k) < 4 \times 10^{-20} \Omega_{\text{PBH}, \text{f}} ( \frac{M_{\text{PBH}}}{10^9 \text{g}} )^{-17/9}\). The study highlights the potential of using GW signals from ultra-light PBHs to probe primordial NGs, providing a new tool for cosmological observations.