  I obtain the effective K\"ahler potential at three-loop order for a general
renormalizable supersymmetric theory containing only chiral supermultiplets.
The three-loop contribution is remarkably simple, consisting of only four terms
involving three distinct renormalized master integrals. In the case of the
Wess-Zumino model with a single chiral superfield, I also obtain the effective
auxiliary field potential at three-loop order, extending previous results at
one-loop order. The method used is inferential, relying on existing knowledge
of the ordinary scalar effective potential.
