The singer's husband turned 42 on Thursday.
The couple has been married since 2014 and share three kids together -- 9-year-old Maxwell, 8-year-old Ace and 2-year-old Birdie. In her birthday tribute to him, Simpson said she prayed for him and that she was born to love him.
"Forty-two years ago today you were born and without a doubt I know that God created and shaped you to be my purest love, truest companion, my forever person, my ALL in everything, my everyday and night answered prayer before I even knew the words to speak," she wrote. "The gift of life began with your first breath to bring forth my purpose to be brought into this life. I truly was born to love you. As a child I talked to God asking for you and you found me when my heart least expected eternal intimacy. I am graced to be living within your soul and you within mine until the end of time."
"I am HAPPY it is your BIRTHDAY...the blessed day this world received the gift of you is the greatest day of the year for so many, but especially for your fortunate wife and our beautifully perfect children," she continued. "I love you. Maxwell loves you. Ace loves you. Birdie loves you."
The feeling is definitely mutual. In July, Johnson Instagrammed gorgeous wedding photos in honor of their seventh anniversary, writing, "Jessica, I love you. Seven years into marriage and you still make me laugh just as hard as day one. ... Our kids bring us so much joy and they could not be luckier to have such a fiercely empowered, unique, beautiful mama. I love you, babe!!!"
In a February 2020 interview with ET, Simpson said her connection with Johnson was "instant" when they met in 2010.
"I think he moved in, like, a month later!" she shared. "So, we knew. When you know, you know. Especially both of us. We had been through a divorce, we had other relationships. We knew exactly what we wanted in a person, in a companion, and exactly who we wanted to raise children with. We were that for each other. Through all of this, we've only become stronger."
Simpson said her husband's love for her is "unreal."
"The pride that he takes in our love and in me, as a woman, is so sexy and it is so empowering, because he just knows that this is my calling," she said. "He knows that this is my path and he's just there to hold my hand through it. He's really the backbone to who I am, because anytime I feel like I can't stand, he's there to hold me up and tell me that I actually can."