  We study $T\bar{T}$-deformed $O(N)$ scalar field theory in two-dimensional
spacetime using the functional renormalization group. We derive the $\beta$
functions for the couplings in the system and explore the fixed points. In
addition to the Gaussian (trivial) fixed point, we find a nontrivial fixed
point at which a new universality class exists. The deformation parameter
becomes relevant at the nontrivial fixed point. Therefore, the $T\bar
T$-deformed scalar field theory in two-dimensional spacetime could be defined
as a nonperturbatively renormalizable theory.
