Lewis proposed to his bride-to-be in the most romantic setting in the world — in front of the Eiffel Tower in Paris, where the a capella group is set to perform a show on Monday, May 30.
"She said yes," Lewis wrote on Twitter, as Maldonado, 24, shared a picture of her look of surprise as he got down on one knee. She later tweeted a line from the song "Nature Boy": "The greatest thing you'll ever learn is just to love and be loved in return."
The pair, pictured above after a friend's wedding on New Year's Eve 2015, also posted a pic of their two dogs appropriately attired in Paris-themed outfits along with a sign saying, "Mom said yes!!!"
"No words could begin to describe the feelings and impact you have had on my life over the past 2 and a half years, but I'll do my best," he wrote. "In august of 2013, I was blessed with the opportunity to meet you, the most incredible woman in the entire world. Since that very day not a moment has passed where you haven't consumed my entire being with your love, support, and friendship."
"What we have is special," he continued. "It's something I will never take for granted — and although there have been countless times something has tried to get in our way and pull us apart, the only thing that matters is that we never listened. We are here, and each day we become closer, and what we have built together continues to grow stronger."
"You deserve nothing but the best, and no matter what life brings to us, I promise to give you nothing but my best. I want nothing more than to have you by my side for the rest of my life. Our life," Lewis wrote. "Kirstin Taylor Maldonado, my darling, my treasure. Will you marry me?"
Pentatonix are currently on a world tour that will take them to Europe, Japan and the U.S. through November.