Panettiere, star of ABC's "Nashville," made her entrance on "Live with Kelly and Michael" wearing a live boa constrictor to startle Michael Strahan, who is not a fan of snakes.
Kelly Ripa immediately noticed a large diamond ring on her finger, prompting her to say, "I'm sort of distracted, not just by the snake, but there's a very large diamond ring on your finger."
"Does that signify anything? Is that a promise of something?" Ripa asked the 24-year-old actress.
Panettiere confirmed her engagement, but said a wedding date has not been set yet.
The actress first met Klitschko, 37, at a book party for a mutual friend in 2009. The couple announced in May 2011 that they had broken up, but they were seen together in public again in January.
On "Nashville," Panettiere plays Juliette Barnes, young country music star who competes with country's reigning queen, Rayna James, played by Connie Britton.