A new construction of non-Gaussian, rotation-invariant and reflection positive probability measures µ associated with the ϕ 4 3 -model of quantum field theory is presented. Our construction uses a combination of semigroup methods, and methods of stochastic partial differential equations (SPDEs) for finding solutions and stationary measures of the natural stochastic quantization associated with the ϕ 4 3 -model. Our starting point is a suitable approximation µ M,N of the measure µ we intend to construct. µ M,N is parametrized by an M -dependent space cut-off function ρ M : R 3 → R and an N -dependent momentum cut-off function ψ N : R 3 ∼ = R 3 → R, that act on the interaction term (nonlinear term and counterterms). The corresponding family of stochastic quantization equations yields solutions (X M,N t , t ≥ 0) that have µ M,N as an invariant probability measure. By a combination of probabilistic and functional analytic methods for singular stochastic differential equations on negative-indices weighted Besov spaces (with rotation invariant weights) we prove the tightness of the family of continuous processes (X M,N t , t ≥ 0) M,N . Limit points in the sense of convergence in law exist, when both M and N diverge to +∞. The limit processes (X t ; t ≥ 0) are continuous on the intersection of suitable Besov spaces and any limit point µ of the µ M,N is a stationary measure of X. µ is shown to be a rotation-invariant and non-Gaussian probability measure and we provide results on its support. It is also proven that µ satisfies a further important property belonging to the family of axioms for Euclidean quantum fields, it is namely reflection positive.