"Dutton Walker Lane born June 8th, 2021," Lauren, 31, captioned photos in which she and Chris had taken turns holding the baby.
"Your dad and I can't get enough of all 9 pounds of you. Now back to baby cuddles and praising Jesus over and over again for this little miracle!!"
Meanwhile, the 36-year-old country singer posted a video of himself holding his newborn.
"Words can't describe the love i feel inside my heart for this little man! Thanks for all the prayers," Chris captioned the video. "I will never understand how @laurenlane birthed a 9 pound baby! DUTTON WALKER LANE welcome to the world."
The video featured Chris telling fans, "First time holding him."
On Friday, Lauren shared the photo of Chris with Dutton in his arms on her Instagram Stories and she wrote on the image, "Even more in love with you."
She later added, "Still catching up on calls and texts and also figuring out this whole mom thing, but thank you to everyone for all the support and love. We love u."
Lauren revealed she was pregnant with her first child in December 2020, when she posted footage from an ultrasound appointment on Instagram and wrote, "A dream, except I'm not dreaming."
"I'm wide awake," she continued. "Holding your dad's hand, watching you dance around in my belly. Listening to your little heart beat. My new favorite sound. A miracle. New life. Our sweet baby. Thank you Jesus! All the glory belongs to You."
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Chris also shared the same video on his own Instagram at the time and captioned it, "Prayer works! Hope you look like your Mama @laurenlane."
Lauren told Us Weekly in May 2020 that she "wants a lot" of children since the former flight attendant grew up with three siblings.
Lauren previously told People that her gut had been telling her she had a baby on the way and so she randomly took a pregnancy test, which led to a second test for confirmation.
"There really wasn't anything physical happening; I just had a funny feeling I was pregnant," Lauren explained last year.
She added, "I think I took about 10 more still in disbelief! Because I was so early we both were shocked but cautiously optimistic!"
In January, Lauren recalled her journey to get pregnant on social media and how she had "prayed every day for months" to conceive.
Lauren said was beginning to "worry" about her ability to get pregnant when she and Chris were trying for four or five months after she stopped taking birth control, according to Us.
"I couldn't help but compare my situation with those of my friends who it happened very easily for, a lot of the time unplanned," Lauren reportedly shared.
"Mentally, this was a really hard part of the journey. I assumed there was something wrong with me. Chris would see how disappointed and worried I would get, and I could tell he felt really bad... It took a couple months of [ovulation strips and progesterone tests], but I think [that] really helped. That confirmation calmed my mind, stress, and worry and it allowed me to let go."
And Chris said at the time he and Lauren were trying for Baby No. 1, "When it happens, it happens."
The "Big, Big Plans" singer went on to say, "I don't really know [the timing]. We don't know if we're completely ready for that yet, but we're also not not going to try either. When it does [happen], it'll be the right time."
Lauren and Chris met in 2015 at a radio event in Austin, TX, but they started out as friends.
The couple went public with their slow-starting romance in November 2018 when they walked the red carpet together at the CMA Awards.
On The Bachelor's 20th season, Lauren and Ben got engaged during the finale that aired in March 2016, and it was widely believed Ben had nothing but the best of intentions and the couple was truly in love. Lauren even moved from the home she loved in California to be with Ben in Denver, CO.
In June 2018, Lauren explained on Reality Steve spoiler blogger Steve Carbone's podcast there was not "one main reason" why her relationship with Ben failed.
"It wasn't this bad blood situation or blow-up fight -- it's nothing I can really pinpoint. It just came down to compatibility... I don't necessarily think at the end of the day we were the most compatible," Lauren said at the time.
"Coming out of a show like The Bachelor is very stressful," admitted Lauren, who said she craved normalcy after getting engaged to Ben.
While Lauren was dealing with negative press -- including gossip about Ben's love for JoJo Fletcher on his season -- and trying to adjust to her new life with Ben in Denver, the pair starred in a Freeform spinoff titled Ben & Lauren: Happily Ever After?, which featured a lot of ups and downs in their relationship.
Lauren had trouble finding a career that suited her and said she didn't want to be Ben's "almost housewife," and Ben had called off their televised wedding due to cold feet.
But Ben is now happily engaged to a woman outside of Bachelor Nation, Jessica Clarke, whom he went Instagram official in January 2019. The pair have planned their wedding for November 2021 after postponing their initial 2020 wedding due to the coronavirus pandemic.