The power was switched off on the Brighton Mainline after the incident at 11.11am this morning.
Police officers and paramedics were called to the scene and services between Three Bridges and Brighton/Lewes were halted.
This afternoon, a British Transport Police spokesperson said: “The woman has now been taken to a place of safety. She is uninjured.”
Earlier today, Southern Rail said: “A person has been hit by a train between Brighton and Three Bridges resulting in some lines being blocked.
“Trains running between these stations may be cancelled, delayed or revised. Disruption is expected until 2pm.
“Some lines have reopened from Three Bridges towards Brighton. However, lines are still blocked travelling northbound from Brighton to Three Bridges.
“We regret to announce of a person being hit by a train between Three Bridges and Brighton. As a safety precaution all trains travelling towards Three Bridges were at a stand between these locations and the power was switched off, while the emergency services dealt this incident.
“If you’ve been affected by what happened on the network today, there is always someone to talk to. You can contact the Samaritans on 116 123 from any phone for a confidential chat.”