In this paper, we study the following nonlinear magnetic Schrödinger equation \(\left( \frac{\varepsilon }{i}\nabla -A(x)\right) ^2u+V(x)u=\lambda f(|u|)u+|u|^{2^*-2}u,\quad x\in \mathbb {R}^N,\) where \(\varepsilon >0\) is a small parameter, \(\lambda >0\) , \(N\ge 3\) , \(V(x):\mathbb {R}^{N}\rightarrow \mathbb {R}\) and \(A(x):\mathbb {R}^{N}\rightarrow \mathbb {R}^{N}\) are electric and magnetic potentials, respectively. Under a global assumption on the potential V, by using variational methods and Ljusternik–Schnirelmann theory, we prove the existence and multiplicity of solutions for sufficiently large \(\lambda \) and small \(\varepsilon \) .