The two country icons tied the knot in 1996 and are proud parents to three daughters -- Audrey, Gracie and Maggie.
The big milestone comes one day after the superstar couple celebrated their inductions into the Music City Walk of Fame in Nashville.
"I've known her forever," McEntire shared, "and I thought, 'Well, shoot, I know everything about Faith.' And I thought, 'Well, wait a minute! Just in case I don't...' I went to Wikipedia and I did find out that she worked at McDonald's before. I didn't know that!" she added, as the crowd laughed.
Hill later said that her employment in the fast food industry lasted exactly two weeks -- a topic that came up again once her husband gave his acceptance speech.
"The best thing that happened to me is in 1996," McGraw recalled. "I went on a tour called the Spontaneous Combustion Tour, and I had a really hot chick on the road with me!"
He continued about Hill, "And I fought and I fought and I fought to stay away from her, as long as I could. And that lasted about as long as her job at McDonald's. I'm not gonna go into detail, but it was a great tour, I can tell you that!"
The rest is country music history.