The last Eurostar trains to leave Waterloo before the London terminal for services to France and Belgium switched to St Pancras set out on their journey on Tuesday.
A large message at Waterloo thanked passengers for their custom over the past 13 years - but reminded them they would still be wanted at St Pancras.
Singer Lily Allen was one of the star attractions as Waterloo and Eurostar made sure the final day was one of celebration as well as reflection.
As the last trains left the station almost 13 years to the day after the service began, it was not only Eurostar and Waterloo who were saying goodbye.
A man had to run to catch the final train from Waterloo - the 1812 GMT service to Brussels - while other people gathered on the platform to wave off loved ones.
Workers began dismantling the Eurostar fixtures and fittings almost as soon as the final train had departed.
On Wednesday morning, Eurostar staff prepared for the first high-speed train to Paris inside the new £800m terminal at St Pancras station.
People boarded the first train, which was due to take two hours and 15 minutes to get to the French capital.
Outside Greenpeace unfurled a banner on the front of St Pancras urging the government not to expand Heathrow.
Staff waved off the train, which left the north London terminal at 1101 GMT.
A passenger cheered as he left the first Eurostar train from Brussels to arrive at the new terminal at St Pancras station.