A mobile safety fall arrest cart is provided. The mobile safety fall arrest cart is configured to move along an edge of an elevated surface as a worker works along the edge. The worker is connected to the cart with a safety line. If the worker falls from the elevated surface, the weight of the worker causes a spike assembly to move from a stowed configuration to a deployed configuration. In the deployed configuration, a spike member engages the elevated surface so as to assist in arresting the worker's fall.