The special moment was then plastered across the big screens for Barker and the crowd to see.
The sign is a reference to one very similar held up in Blink 182′s All the Small Things video.
Fans have since taken to Instagram to share congratulatory messages with the couple.
The Kardashian has three children with ex Scott Disick including sons Mason, 13, and Reign, 8, and her daughter Penelope, 10.
Their nine-year relationship was been shown on Keeping Up With the Kardashians and its numerous spin-offs.
Barker has two children, Landon, 29, and Alabama, 17, with his ex-wife Shanna Moakler.
In April 2021, Kardashian and Barker tied the knot in Las Vegas.
The news of the pregnancy comes after sharing her struggles to get pregnant and her IVF journey.
Last year she announced that she was stopping IVF after 10 months.
“My health is still impacted because it’s hormones, and mentally it definitely took a toll,” she wrote on Instagram.