Nearly monochromatic-red-light-emitting polymers with pendant carbazole and europium (Eu) complex were synthesized and characterized by Fourier transform infrared, elemental analysis (EA), H-1 NMR, C-13 NMR, UV, and gel permeation chromatography. The photoluminescence and electroluminescence (EL) properties of these polymers were investigated. A single-layer light-emitting-diode device of the structure (indium tin oxide/polymer P4/Al) was fabricated, showing the characteristic bright-red EL of the Eu3+ complex at 614 nm at a turn-on voltage of about 17 V. The EL spectrum, current-voltage, and emission-intensity-voltage characteristics of the device were measured.