Trentin forced a selection with an attack on the Côte de Beau Soleil in the final seven kilometres, dragging with him just a handful of riders of which just Kragh Andersen and team mate Niki Terpstra remained at the end.
QuickStep Floors team mate and last year's race victor Fernando Gaviria succumbed to a slippery corner on the same hill and while he was able to remount, he could not make it back to the front to contest a second victory.
The win in the 234 kilometre race was Trentin's sixth victory in just the latter half of this season, including four stage victories at the Vuelta a Espana. It was QuickStep's third win in a row at Paris-Tours after Gaviria's victory in 2016 and Trentin again in 2015.
“The light rain and wet roads made for a strung out bunch," said the 2018 Orica-Scott bound rider. "So on the first hill I said to myself it won’t hurt to give it a go."
"But then I went again and Niki came across. We played perfect tactics and Niki did an incredible work and a provided a superb lead-out in the last kilometre.
"It’s fantastic to end the season in such a manner. I want to thank to Quick-Step Floors for these seven years, it was an honour to ride with them and I’m proud of bringing down the curtain over my time here with a second victory in Paris-Tours."
It was the 52nd professional victory for QuickStep Floors, which included a successful Classics season.
Earlier, Lawrence Naesen (WB Veranclassica Quality Protect), Michael Goolaerts (Veranda's Willems-Crelan), Brian Van Goethem (Roompot-Nederlandse Loterij), Romain Combaud (Delko Marseille Provence KTM) and Stéphane Poulhiès (Armée de Terre) pulled clear after a half an hour of racing. Their maximum advantage of around five minutes fell gradually until they enjoyed just two minutes and 15 seconds, 80 kilometres from the end in Tours.
On the climb in Crochu, 30 kilometres from the finish, only Van Goethem and Naesen remained out the front until they too were caught in the final 10 kilometres.