The 46-year-old singer and 39-year-old television personality voiced their love and gratitude for each other while celebrating their wedding anniversary Wednesday.
Lachey shared a photo of himself and Vanessa Lachey embracing on a beach.
"I feel incredibly lucky to have found my soulmate and ultimate partner in life and love. V, you mean everything to me," Lachey captioned the post.
"No matter what we face, we face it together. Whatever blessing we enjoy, we enjoy it together. With our love and commitment to each other, I know there is nothing we can't get through..... together," he said. "I love you V with all that I am. I always will! Happy Anniversary."
Vanessa Lachey posted a picture of herself and Lachey dancing at their wedding.
"Today, I say 'Thank You.' Thank You for this Beautiful Life & Marriage," she wrote. "Thank You for the unconditional Love you give to me and our 3 crazy kids. Thank You for the hard work you put into Us and yourself daily. Thank YOU for keeping all your vows we shared on this day nine years ago. Thank you for it ALL. Happy Anniversary, My Love! I Love You!!!"
Actresses Hilarie Burton and Jamie Lynn Sigler were among those to congratulate the Lacheys in the comments.
"Beautiful!!!!" Burton wrote.
"Happy happy anniversary," Sigler said.
Lachey and Vanessa Lachey married in 2011 and have three children, sons Camden, 7, and Phoenix, 3, and daughter Brooklyn, 5. Vanessa Lachey shared a photo of Lachey with their kids while celebrating Father's Day in June.
"Happy Father's Day to the GOAT! We Love (and NEED) You, Daddy!" Vanessa Lachey wrote.
"I've said it before and I'll say it again... EVERYTHING good in my life is because of You! Thank You, Baby for this life, our babies & your relentless dedication to our family. Happy Father's Day, My Love," she added.