The British team has signed up Belgian rookie Vandoorne, 24, to replace Button next year, but the 36-year-old F1 veteran is also under contract and according to McLaren will be ready to drive if necessary.
Asked by France's Auto Hebdo if that means extra pressure for Vandoorne, the 24-year-old answered: "No, I think [Button's deal] is a good solution.
"Jenson is one of the most experienced drivers on the grid, he knows the team and is actively involved in the development of the new car. It would be silly to not benefit from that.
"His experience will be good for the team and I can learn a lot from him too."
In fact, Vandoorne said that the overwhelming emotion when McLaren recently announced his deal was relief.
"I felt relieved to sign a contract even though I had to pinch myself," he said.
"In Formula 1, even if you didn't doubt that I would get a place, nothing is certain until a contract is signed. So the last few months were not easy but now that everything is official it's like a weight off my shoulders."
This year's championship continues next weekend with the Malaysian Grand Prix.