Pultruded glass fiber reinforced polymer (GFRP) sections are increasingly used as load bearing elements in civil construction. Their low elastic modulus and thin-walled nature make these sections prone to buckling phenomena when loaded in compression. This paper presents a study on the axial compression behavior of the pultruded GFRP channel sections. Two variables were considered including column slenderness ratio and wall width-to-thickness ratio. Therefore, four channel sections with different dimensions were selected. Seven column lengths ranging from 100 mm to 1400 mm were used for each channel section under axial compression. Three failure modes were observed including section crushing, local buckling and global buckling which were highly related to the column slenderness. Load-displacement curves and compression capacities were reported and compared. Finally, existing analytical design equations in the literature were validated using experimental results. Recommendations on compression design of pultruded GFRP channel sections were made based on the results in the current study.