  We consider a generic first-order phase transition at finite temperature and
investigate to what extent a population of primordial black holes, of variable
masses, can affect the rate of bubble nucleation. Using a thin-wall
approximation, we construct the Euclidean configurations that describe
transition at finite temperature. After the transition, the remnant black hole
mass is dictated dynamically by the equations of motion. The transition
exponent is computed and displays an explicit dependence on temperature. We
find the configuration with the lowest Euclidean action to be static and $O(3)$
symmetric; therefore, the transition takes place via thermal excitation. The
transition exponent exhibits a strong dependence on the seed mass black hole,
$M_+$, being almost directly proportional. A new nucleation condition in the
presence of black holes is derived and the nucleation temperature is compared
to the familiar flat-space result, i.e. $S_3/T$. For an electroweak-like phase
transition it is possible to enhance the nucleation rate if $M_+ \lesssim
10^{15} M_{\rm P}$. Finally, we outline the possible transition scenarios and
the consequences for the power spectrum of stochastic gravitational waves
produced due to the first-order phase transition.
