The 39-year-old singer marked the special occasion on Sunday with an Instagram post showing off her thoughtful gift from Eric Johnson, 40.
In the pic, Simpson and her husband, a former football pro, smiled as they stood together behind a large purple crystal, which was shaped like a butterfly.
“Eric Johnson, my Husband, I love you,” the “With You” singer wrote in the caption. “6yrs ago today I married my perfect soulmate. Our unity was written in God’s sky of colliding stars. Together we manifest dreams, nurture desire, and hold space. Destined, it always has been and always will be, forevermore.”
The actress explained that the crystal butterfly is a “dream gift” of hers, which “anyone who knows [her] at all” would recognize.
Simpson finished off the post with a quote: “‘Whatever our souls are made of, his and mine are the same.'”
The romantic line comes from the classic novel “Wuthering Heights” by Emily Brontë.
Simpson and Johnson began dating in 2010 and married in 2014. They share three children: Maxwell, 8, Ace, 7, and Birdie, 1.
“In terms of my marriage to Eric, I have never felt more myself or more free,” she explained in February. “Eric and I have a true mind, body [and] soul connection.”