The exact solution of the spectral problem for an infinite (2m,m) carbon nanotube (CNT) is obtained from the analytic solution to the Schrödinger equation for the tight‐binding Hückel‐type Hamiltonian. Explicit expressions for Green's functions of chiral (2m,m) CNTs are obtained and the electronic structure of these CNTs is discussed. The (2m,m) nanotubes with a medium‐chiral angle equal to 19.1° are considered as an intermediate case between the thoroughly investigated achiral armchair and zigzag nanotubes.