First order cosmological phase transitions in beyond the Standard Model theories may trigger the
production of a stochastic background of gravitational waves (GW) which could be probed by near future experiments. Since many proposals for dark sectors involve QCD-like, strongly interacting theories, it is crucial to study this issue under the lens of a non-perturbative approach. We use the holographic correspondence to study finite temperature phase transitions and the related GW spectra within the top-down model which mostly resembles large N QCD at low energy. The model displays both a confinement/deconfinement and a chiral symmetry breaking/restoration first order transition. Depending on the model parameters, these can happen either at the same or at different critical temperatures. We study the nucleation of bubbles of true vacuum in the metastable phase in both cases and determine the relevant parameters entering the expressions of the GW spectra due to bubble collisions and sound waves. A large region in the parameter space of the model provides GW signals which may be accessible by near future experiments of different classes.