Geological carbon sequestration using basalts provides a solution to mitigate the high CO₂ concentration in the atmosphere. Due to the long timespan of the GCS, it is important to understand the long-term deformation of the reservoir rock. Here, we studied the creep of basalt with fluid presence. Our results show presence of fluid weakens the rock and promotes creep, while the composition only has a secondary effect and demonstrate that the governing creep mechanism is subcritical microcracking.