This paper deals with the parabolic–elliptic Keller–Segel system with signal‐dependent chemotactic sensitivity function,
{alignedrightutleft=Δu−∇⋅MathClass-open(uχMathClass-open(vMathClass-close)∇vMathClass-close),rightleftx∈Ω,t>0,rightright0left=Δv−v+u,rightleftx∈Ω,t>0,under homogeneous Neumann boundary conditions in a smooth bounded domain ΩMathClass-rel⊂double-struckRnMathClass-punc,1emnbspnMathClass-rel≥2, with initial data u0MathClass-rel∈C0(trueΩ̄) satisfying u0 ≥ 0 and MathClass-op∫Ωu0MathClass-rel>0. The chemotactic sensitivity function χ(v) is assumed to satisfy
0MathClass-rel<χ(v)MathClass-rel≤χ0vkMathClass-punc,1emquadkMathClass-rel≥1MathClass-punc,1emnbspχ0MathClass-rel>0MathClass-punc.The global existence of weak solutions in the special case χ(v)MathClass-rel=χ0v is shown by Biler (Adv. Math. Sci. Appl. 1999; 9:347–359). Uniform boundedness and blow‐up of radial solutions are studied by Nagai and Senba (Adv. Math. Sci. Appl. 1998; 8:145–156). However, the global existence and uniform boundedness of classical nonradial solutions are left as an open problem. This paper gives an answer to the problem. Namely, it is shown that the system possesses a unique global classical solution that is uniformly bounded if χ0MathClass-rel<2n1emnbsp(kMathClass-rel=1)MathClass-punc;1emnbspχ0MathClass-rel<2nMathClass-bin⋅kk(kMathClass-bin−1)kMathClass-bin−1γkMathClass-bin−11emnbsp(kMathClass-rel>1), where γ > 0 is a constant depending on Ω and u0. Copyright © 2014 John Wiley & Sons, Ltd.