In a new blog post on her website, Keibler, 35, shows off her toned body in a pink sports bra and tiny black shorts, and reveals how she lost all the baby weight so quickly.
Keibler credits her incredible bounce-back to keeping her diet healthy during pregnancy.
"I've always been a healthy eater, but now, it was even more crucial to be aware of everything I was consuming," she recalls. "My diet -- during and after pregnancy -- was the major reason I was able to shed the baby weight. In fact, what I put into my body was the biggest single thing that helped me get back in shape."
And of course, she also regularly exercised.
"I wanted to stay as active as possible, since I had been told regular exercise would make labor easier -- and also help take the weight off," she says. " [My husband] Jared and I hiked hills and took walks together. Walking a few miles every day was an essential part of my daily routine and I walked until (and on) the day I went into labor. I also went to Pilates three times a week."
But surprisingly, she waited four weeks after giving birth to start exercising again.
"The day I was cleared to exercise, I started walking and working with my trainer Nonna Gleyzer to properly re-attach my ab muscles," she says. " ... In fact, my abs are in better shape now than before I got pregnant!"
On her blog, Keibler shares her post-baby workout routine to readers who may want to achieve the same post-pregnancy weight loss. It's a low-impact plan, which includes ballet moves like the Ronde de Jambe ("Facing a ballet barre in fifth position (on your tippy toes with one foot placed in front of the other while touching) kick left leg straight up while keeping stomach tight and back straight") as well as side-ups and pull-ups.
"More than three months have passed since I gave birth, and I’m happy because my body is back," she says. "I feel strong, flexible, and very high energy. ... I feel fortunate to have the body that I do -- but I work hard for it."
Last July, ET caught up with the model/actress to talk about her new gig as the host of Lifetime's reality series Supermarket Superstar, which focused on food entrepreneurs.