The highly-anticipated bout will see Joshua and Parker put their IBF, WBA Super, IBO and WBO belts and unbeaten records on the line, as both fighters aim to become the first undisputed heavyweight champion since Lennox Lewis in 1999.
Many pundits out of the UK believe Joshua's size and skill will prove too much for Parker at the Principality Stadium on April 1 (NZ time), but Wilder has a different perspective.
Speaking to Andrew Gourdie and Jim Kayes on RadioLIVE's Sunday Sport, Wilder issued a warning not to be deceived by the Briton's chiselled physique.
"Just because a person looks more muscular and looks like they have it all down pat doesn’t mean they are going to destroy everybody," he told RadioLIVE.
"I tell people that I would rather be the part then look the part, looking the part isn’t going to get me nowhere. I've seen many people look the part but when it's time to perform in a place where it really matters, they can't pull the trigger.
"I think Parker is good at where he is to be a little bit slender, not having too much muscle because when you start bulling too much muscle mass your flexibility starts to decrease."
Wilder, who is also unbeaten in his professional boxing career, admitted he has been in contact with the South Aucklander regarding aspects of his game to work on for the fight.
"Parker will also have to be mobile which I think he will do a pretty good job of. The things I'm telling you now I've told him before, because we talk.
"He is going to have to continue to punch while he moves and keep his head moving. If he can do that, he will see openings and see some of the weakness Joshua has.
"On the flip side Joshua is going to have to be more flexible, he is going to have to move his head more. I hope his conditioning is well put because he is going to need that…if he doesn't have that there could be problems, if Parker knows how to handle the situation."
The 32-year-old will be working with Sky Sports UK for the fight coverage, and will likely face the winner later in the year. He's not shy in admitting that he's hopeful that Joshua reigns supreme in the ring.
"I'd be lying if I said I want Joseph Parker to win. But I wish Joseph Parker the best.
"But the reason that me and Joshua is a highly anticipated fight is that the world wants to see and it will bring the heavyweight division back to its top peak.
"But anything can happen in boxing and we all have to keep in mind that the head isn’t meant to be hit in the first place, so if you get hit in a certain way you can go. This is a brutal sport."
Wilder is currently preparing for his 40th career fight against Luis Ortiz at the Barclay's Centre in Brooklyn.