We investigate the existence, multiplicity and concentration of nontrivial solutions for the following fractional magnetic Kirchhoff equation with critical growth:a positive continuous potential verifying the global condition due to Rabinowitz [50], and f : R → R is a C 1 subcritical nonlinearity. Due to the presence of the magnetic field and the critical growth of the nonlinearity, several difficulties arise in the study of our problem and a careful analysis will be needed. The main results presented here are established by using minimax methods, concentration compactness principle of Lions [43], a fractional Kato's type inequality and the Ljusternik-Schnirelmann theory of critical points. 2010 Mathematics Subject Classification. 35A15, 35R11, 35B33, 35S05, 58E05.