Travellers will be able to get from the French capital to Rennes, in Brittany, in under an hour and a half, and to the south-western wine capital in a little over two hours.
The opening is highly anticipated but comes as the state-owned rail network, the SNCF, struggles to keep itself out of the headlines.
Three days before of the opening of the Tours-Bordeaux line that will make the two-hour journey possible, the SNCF says some cities on the line still owe the agency 350 million euros in previously promised funding.
Fifty-eight municipalities had promised to contribute a total of 1.3 million euros for funding the construction of the project but when the SNCF asked them to put it in writing and pay up, only 33 obliged.
In May a Paris court ordered 10 local authorities to pay 110 million euros owed to the SNCF.
Negotiations have since begun between the SNCF and nearby communities to recover the remaining 240 million euros.
Many local councils say that they want more frequent service at their local stations, instead of more direct trains to Paris that the SNCF had previously proposed.
Another setback for Bordeaux-Toulouse link
A Bordeaux court upheld arguments Thursday from two cities in Southern France against the future development of a high-speed railway between Bordeaux and Toulouse.
Gironde and Lot-et-Garonne disputed that a high-speed line linking Bordeaux-Saint-Jean train station to Saint-Médard-d'Eyrans, some 15 kilometres to the south, "has no reason to exist". They suggested modernisation of the existing line between the two stations.
The ruling allowed for the scrapping of a Declaration of Public Utility (DUP) between the two municipalities and the SNCF.
The agreement is essential and must be obtained before any construction can begin.
The SNCF had hoped to open the high-speed line by 2024.
SNCF chief wants more affordable TGV trains
SNCF President Guillaume Pepy says there will be no more annual price increases for TGV trains.
Instead Guillaume says that the public company hopes to cut its own costs in order to pass the savings on to its customers.
"We have only one strategy, it is to lower our costs in order to lower prices" he said on RTL Radio.
Paris-Bordeaux losses expected
The public railway company expects to lose 90 million euros in the second half of 2017 from its Paris-Bordeaux route, which is being built and operated under a public-private partnership with the Lisea consortium, led by the Vinci group.
Two thirds of SNCF railway services lose money, for example Lille-Lyon, Paris-Metz-Luxembourg, Strasbourg-Nantes, Paris-Reims or Paris-Côte d'Azur.