  We introduce an explicit description of the $\Phi^4_3$ measure on a bounded
domain. Our starting point is the interpretation of its Laplace transform as
the value function of a stochastic optimal control problem along the flow of a
scale regularization parameter. Once small scale singularities have been
renormalized by the standard counterterms, $\Gamma$-convergence allows to
extend the variational characterization to the unregularized model.
