France's national rail operator says it has finished repairing infrastructure damaged in a suspected coordinated arson attack on Friday.
State-owned SNCF said most trains were running as planned on Sunday and full service will resume on Monday.
Police are still searching for the perpetrators behind what French ministers and officials have described as "sabotage" designed to paralyse high-speed TGV lines running to and from Paris.
Hundreds of thousands of people were caught up in the resulting disruption, which came hours before the opening ceremony of the Olympic Games in the capital.
SNCF said staff have been working around the clock to manually repair fibre optic cables, which were targeted on the North, Brittany and South-West lines.
Rail workers foiled an attempt to destroy safety equipment on a fourth line.
On Sunday, the rail company said the main western line from Paris was operating almost as normal, while three out of four TGV trains were running on the northern line from Lille, with no delays expected.
SNCF said around 250,000 passengers were affected on Friday, while junior transport minister Patrice Vergriete estimated as many as 800,000 people could be impacted over three days.
Eurostar - which runs international services from London to Paris and uses a high-speed line in France - was also impacted. It said one in four of its trains would not run over the weekend.
Among those caught up in the disruption on Friday was Prime Minister Sir Keir Starmer, who had planned to travel to the Games' opening ceremony via train but was forced to fly instead.
He told the BBC: "I’m not going to pretend it wasn’t frustrating because it was, and for very many people it made travel so much harder."
The Paris prosecutor's office has opened a criminal investigation into what happened, which is being overseen by its organised crime office.
