Consider a symmetric non-local Dirichlet form (D,D(D)) given byD(f,f)=∫Rd∫Rd(f(x)−f(y))2J(x,y)dxdy with D(D) the closure of the set of C1 functions on Rd with compact support under the norm D1(f,f), where D1(f,f):=D(f,f)+∫f2(x)dx and J(x,y) is a nonnegative symmetric measurable function on Rd×Rd. Suppose that there is a Hunt process (Xt)t⩾0 on Rd corresponding to (D,D(D)), and that (L,D(L)) is its infinitesimal generator. We study the intrinsic ultracontractivity for the Feynman–Kac semigroup (TtV)t⩾0 generated by LV:=L−V, where V⩾0 is a non-negative locally bounded measurable function such that the Lebesgue measure of the set {x∈Rd:V(x)⩽r} is finite for every r>0. By using intrinsic super Poincaré inequalities and establishing an explicit lower bound estimate for the ground state, we present general criteria for the intrinsic ultracontractivity of (TtV)t⩾0. In particular, ifJ(x,y)≍|x−y|−d−α1{|x−y|⩽1}+e−|x−y|γ1{|x−y|>1} for some α∈(0,2) and γ∈(1,∞], and the potential function V(x)=|x|θ for some θ>0, then (TtV)t⩾0 is intrinsically ultracontractive if and only if θ>1. When θ>1, we have the following explicit estimates for the ground state ϕ1c1exp(−c2θγ−1γ|x|logγ−1γ(1+|x|))⩽ϕ1(x)⩽c3exp(−c4θγ−1γ|x|logγ−1γ(1+|x|)), where ci>0(i=1,2,3,4) are constants. We stress that our method efficiently applies to the Hunt process (Xt)t⩾0 with finite range jumps, and some irregular potential function V such that lim|x|→∞V(x)≠∞.