The couple married in 2009 and welcomed son Gunner last month.
Speidi turns nine!
Heidi Montag and Spencer Pratt celebrated nine years together on Monday. The couple married on April 25, 2009.
Montag took to Instagram to celebrate the occasion with a touching message to Pratt alongside a sweet family portrait with their 7-week-old son, Gunner.
"Happy 9 year anniversary! It was love at first sight. I knew my life would never be the same," she wrote. "You are my soulmate, my heart, my soul, my best friend, my everything."
"We have fought through so much to be together. Every moment of it has been such a blessing. I knew I had to follow my heart and have faith in love and in you. Best decision of my life," Montag continued. "Thank you so much for our son! This is been the best 11 years of my life. It continues to get better every moment, every day, every year."
"I love you more than I’ll ever be able to tell you! I didn’t think our love could get deeper until @gunnerpratt arrived! Not only are you the most amazing husband, you are the most amazing father!" she concluded. "I can’t wait to see the journey life has in store for us!"
The Hills stars welcomed Gunner on Oct. 1, but Montag recently told ET that she was already working on convincing Pratt to have another baby.
"It took me a lot of years to convince Spencer to have baby No. 1, so I'm just trying to put it in there," she said with a laugh. "[We won't be having another kid] anytime soon, but you gotta work on these things early, is what I've learned."
See more on the couple in the video below.