The 59-year-old television personality and 44-year-old actress marked the occasion by dedicating sweet posts to each other on their wedding anniversary Wednesday.
"@PortiadeRossi and I got married 9 years ago today. Being her wife is the greatest thing I am," DeGeneres captioned a photo on Instagram from their wedding.
De Rossi followed by posting a picture of herself and DeGeneres at dinner. She joked about her long-lasting relationship with the star in the caption, saying the photo was taken with an actual camera.
"We've been together so long that not only do we look like kids in this picture, but it was taken with a camera! Happy 9th, Thing," she wrote.
Singer Joshua Radin, who performed at the pair's wedding, was among those to wish the couple well. DeGeneres re-posted Radin's anniversary message on her own account.
"Nine years ago today, these two incredible women got married and asked me to sing some of my songs to them while they were celebrating their most special day," Radin wrote. "It's still one of the most fun things I've ever done. Happy anniversary @theellenshow and @portiaderossi."
DeGeneres and de Rossi tied the knot at their Los Angeles home in 2008 after four years of dating. The television personality denied amid divorce rumors in 2015 that she and de Rossi have ever been close to splitting.
"There's never been a point where we were breaking up or divorcing or fighting. None of these stories are even remotely true," she said in an interview with Today.