Guernseyman Priaulx has spent the last few days training on the island with 2009 world champion Button, who finished runner-up to Sebastian Vettel last season.
With six world champions on the grid for the first time in F1 history this year, the competition is likely to be more fierce than ever.
Multiple World Touring Car champion Priaulx, who this year competes in DTM as BMW enter the fray for the first time, at least feels Button will be able to withstand the mental pressure.
"He joined McLaren as the guy supposedly slower than Lewis (Hamilton), and I am very pleased to say he shut up all his critics very quickly," Priaulx told Press Association Sport.
"I always knew he would, but it's nice to let your results do the talking.
"He has the utmost respect for Lewis, and he knows he is massively quick, but Jenson is also quick and clever, and you need both to win races and championships.
"I've enjoyed watching him develop at McLaren, and I said to him last year 'I think you're still improving', and he has proved to me he is.
"As for this year, he's very positive. Mentally I don't think I've ever seen him in a better place, the last six months especially, and I've known him since he was 21.
"I'm sure he'll be as strong, if not better."
As someone who regularly competes in triathlons, Button's physical prowess has never been in question, so for Priaulx training with the 31-year-old has been an interesting experience.
"Whenever he is in Guernsey we train together. I manage to hang on to his back wheel on a bike. He's a strong kid," added Priaulx.
"If he wasn't a race driver I'm sure he would be a professional triathlete.
"But I can make him sweat, have a session with him. It's not like we go out and he is having to wait for me.
"But it's been great to train with him in Guernsey because you also like to know where your fitness is.
"I've trained a lot throughout my career, but to train with someone like Jenson, who has a very high level of fitness, it gives you a target.
"And it's good to chat as mates, to understand his mindset going into this year after a brilliant season last year."
Priaulx, though, faces a potentially tough season in DTM as BMW attempt to keep pace with Mercedes and Audi who are now stalwarts in the series.
"It will be my 10th year with BMW, and this is a new challenge, but it's about time something new came along," said Priaulx.
"I had a great period in World Touring Cars, and I will always look back very favourably on that period of my career.
"But it's a great time to be going into DTM, the series is growing, with three major manufacturers, and it's going to be really tough and competitive.
"But it's going to be great to be involved in a series that takes you to that level."