In vivo biological imaging in first near-infrared window (NIR-I, 700-900 nm) and the second near-infrared window (NIR-II, 1000-1700 nm) using conjugated polymers have recently attracted great interest. Compared with imaging in visible region (400-700 nm), NIR bioimaging can provide deeper tissue penetration and higher spatial resolution due to fewer scattering of longer-wavelength photons. Moreover, most of NIR-I and NIR-II conjugated copolymers have been reported with tunable excitation and emission of fluorophores through modification of their donor-acceptor structures. In this minireview, we focus on the recent advances on chemical synthesis of conjugated polymers and their biological imaging in NIR-I and NIR-II windows.