The future of the 2009 world champion has been the subject of intense speculation with reports suggesting Button would call time on his 16 season F1 career at the Japanese Grand Prix.
“Yes, what more do you want?” Dennis told Sky F1 when pressed if Button and Alonso would be in the McLaren cars next season.
“At the end of the day we have Fernando contracted for three years and Jenson contracted for two and we have three young drivers all at various stages of their careers all doing well.
“We know where we are going and what we are doing.
“What is simpler than they have all got contracts and they are all going to live by them.”
Dennis confirmed that McLaren did have an option on Button's contract before revealing that he told the 35-year-old this week that his deal would remain intact for next year.
“We did have an option to terminate Jenson's contract and I told him earlier this week that was not going to happen and I think he was pleased and maybe I should have told him a bit sooner,” added Dennis.
“The contract is completely intact and is going to be unchanged I've spoken to Jenson about it and he is happy.
“I probably should have (told him earlier).
“In any relationship, if you feel that the other party is not particularly comfortable and you are doubting that other party's commitment, that is not a good way forward.
“If that doubt is removed things change. ‘Do you want me? Do you care? Do you believe in me?' That is the kind of sentiment I believe was in Jenson's thinking.”