- When People magazine voted him one of the 50 Most Beautiful People in 2003, he was asked what beauty products he used, and replied, "The closest thing I use to beauty products is the grease on the pizza from John's Pizzeria."
- On Ashley Williams' character on Good Morning, Miami: "Hers is a combination of wisdom and innocence."
- "I just give off this kind of feminine vibe which has... served me so well with women in my life."
- "In high school, I was a total jock/extracurricular nerd/just plain nerd. When I got to college, I realized that building a resume to get into a good school was no longer necessary. I had already gotten into one. I might as well follow my bliss."
- On working with Penelope Cruz in Woman On Top: "I can't say enough nice things about her. She is amazing. You would think, looking at her, "Well, she can't be smart, funny, and a good actress," but she is all these things and more. She's great at imitations, dancing, partying. And she's a great person, too. She doesn't do it for show. One day when we were shooting in Pellerinho, a small town in Bahia, Brazil, we're hanging out on a street corner and there's this little boy who's dirty, dressed in rags, who is begging. She takes him by the hand and walks him to a sandwich shop and buys him two roast beef sandwiches. There's no one around, writing an article about her, this is just Penelope being herself."
- "Once you become an actor, it's important to take care of yourself. I live in Santa Monica, where I can mountain bike, hike and go running on the beach. I like a nice sunset jog."
- (On his Jake Silver character on "Good Morning, Miami"): "When it comes to producing a morning show, Jake is your man,” says Feuerstein. “He’s smart, ambitious and honest but when he meets the love of his life, the only thing he can produce is a big, fat foot in his mouth!”
- On In Her Shoes: "It's not a chick flick. Guys should go see this movie because if anybody has a brother out there or is interested in their relationship with their family - or enjoys seeing Cameron Diaz in a bikini - this will appeal to you."
- "I get razor bumps. Those bumps are my superficial vanity issue."
- On the screenplay for In Her Shoes: "When I read the script I was crying. I loved this story, so to be part of it in any capacity was a dream for me. But to get to play the one male lead in this movie opposite Toni Collette... Playing a guy who loves food, which is me. Playing a guy who is upfront and honest about what he feels. It was just a dream for me."
- On starring in the upcoming TV show 3 lbs.: "Pronouncing the words alone requires one-millionth of the effort that a brain surgeon has to make to become a brain surgeon, but it still sucks. It's still tough."
- "When Mark's not beautiful, he's adorable," says Ashley Williams, his costar on NBC's new hit sitcom Good Morning, Miami. "When he's just waking up from a nap and his hair is all scruffy and his eyes are having trouble staying open, he's cuddly. Only Mark can pull off the ragged look. He really pays attention to people. And he has an incredible knack for complimenting women. I'll come into work and he'll say, 'Great lip gloss, Sweetheart.'"--Ashley Williams on Mark.