As a geocell reinforced structure can be subjected to earthquake and pullout loads during its life time, it is obligatory to assess the pullout capacity and soil-geosynthetic interaction of geocell under cyclic loads. This research investigated the cyclic and post-cyclic pullout behavior of geocell in cohesionless soil using a series of 24 multi-stage pullout tests. The results indicated that the ultimate post-cyclic pullout load was less than the monotonic pullout load. This was the result of a reciprocating motion from loading caused by the interlock between the geocell infill soil and the surrounding material, which weakened and broke during the cyclic phase. It was found that, as the grain size of the soil increased, the interlocking strength increased and consequently the ultimate post cyclic pullout load increased. The soil particle size had a significant effect on the cumulative displacement during the cyclic phase. Furthermore, the increases in the loading amplitude and the number of cycles decreased the interlocking resistance of the infill soil with the surrounding material, which decreased the ultimate post-cyclic pullout load. The effect of the loading frequency likely depended on the geocell infill soil density.