While the girl-power gathering sent fans into a frenzy, none of the A-list performers on stage got nearly the reaction that Obama enjoyed.
All four women explained the impact of music on their lives, with Obama speaking last. As she shared her first words, the audience erupted into wild cheering that lasted so long, Obama herself had to try to calm the crowd.
"From the Motown records I wore out on the South Side to the 'who run the world' songs that fueled me through this last decade, music has always helped me tell my story," Obama shared, smiling. "Music helps us share ourselves. Our dignity and sorrows, our hopes and joys. It allows us to hear each other and to invite each other in. Music shows us that all of it matters."
Without a doubt, the beloved former first lady's cameo appearance will go down as one of the night's biggest surprises, and viewers couldn't contain their excitement, making the 55-year-old revered political figure a trending topic on Twitter within minutes.
"This is how I start most of my mornings off -- in grounding and gratitude and asking for clarity," Keys wrote on Instagram alongside a contemplative snapshot of herself in a white hoodie. "Envisioning the day and putting light around it. Today more than ever I wanted to share the energy I prayed for and called for all of us to feel."
"So just know your day is surrounded by love, light and greatness!!!" she added. "I called on it for all of us... Here’s to the best day of our lives so far!!"
"It's a little bit of a second home to me. And I feel so blessed to be able to be coming now, just in support of so many amazing people that are honored -- especially so many women that are [going to be] honored -- and are gonna be celebrated that night," she shared.
"I want to celebrate! I want to be the one that really just continues to reach out to the people that I love and admire and my friends, and just be able to create an amazing energy," she added.
Check out the video below for more on this year's big show.