The Magic Mike actor told The Guardian that accepting a string of rom-com roles helped him find acting work again.
"Truth is, I was in a colder part of my career at the time," he said.
"I was coming off, what was it, U-571? I had to try different things. I did action movies, crime; and then I did Wedding Planner.
"I thought, let's go see what it's like to just be light; never done that before. And then, s**t… it made a whole bunch of money, and they came back and offered me more."
Despite taking on darker projects recently - such as his latest role in William Friedkin's Killer Joe - McConaughey was quick to defend the romantic comedy genre.
"Rom-coms are hard in a lot of ways," he said. "It's easy to demean them.
"I take the comedy real seriously. There's a whole plan behind it. Even though those characters look like I'm just skating through, there's a design behind it."
He added: "I did a few romantic comedies. I enjoyed them. They paid well; they were fun, [but] I didn't know if I wanted to do any more.
"I decided to sit out, and I had to endure for a while. Another one comes with a big old paycheck; I had to say no. I was looking for something to be turned on by."
McConaughey also admitted that although he is thrilled to be branching out into different genres, when he was first approached with the script for Killer Joe, he "didn't like it all".
""It made me sick... I wanted to get a steel brush and clean myself off," he said.
"But afterwards... Friedkin talked to me about how absurdly funny he thought Tracy Letts was, so I reread it and it clicked."
Killer Joe is out in cinemas now. Watch a Digital Spy exclusive clip from the controversial thriller below: