Both Manganiello and McConaughey star in Magic Mike, which centres on a group of male strippers working in a club owned by former stripper Dallas (McConaughey).
When New York Magazine's Vulture asked about McConaughey's "insanely committed performance", Manganiello said: "Well, first of all, he needs to be nominated for everything this year. I mean, I'm serious. That guy, it's amazing.
"To have one of the biggest stars of all time show up with that level of commitment, it sets the tone, it validated everything that I thought about the script.
"You show up on set and the biggest star in the movie is in a yellow, midriff-revealing halter top, bike shorts, ballet slippers... you look at him and go, 'Okay, this s**t? We're playing for real here'. Any time I spent with McConaughey, I treasure. Just hearing him talk about the world is amazing."
Manganiello, who has showed off his body numerous times in his film projects, also revealed that he was once a skinny teenager.
"I mean, everyone walks into the gym on day one skinny or fat," he shared. "Arnold Schwarzenegger walked into the gym skinny at 15 or 16, and I was that way, too. I didn't fill out until I was 28, when I was working this crazy construction job, and if the role on True Blood didn't require it, that's not necessarily what I would look like.
"I've always been an athletic guy, but the extent to which I go for True Blood or for Magic Mike is because of the role that I'm playing."
The Steven Soderbergh-directed film opens in June 29 in the US and July 11 in the UK.
Watch the trailer for Magic Mike below: