The Poosh founder’s 9-year-old daughter Penelope – whom she has with ex-partner Scott Disick – and the Blink-182 drummer's daughter Alabama, 16, whom he has with second wife Shanna Moakler, were the couple's flower girls at a lavish ceremony at the Dolce and Gabbana-owned L'Olivetta villa in Portofino on Sunday.
The pair were seen walking down the aisle in mushroom-coloured netted gowns embroidered with red poppies, with red roses in their hands and a single red flower in their hair.
Barker's step-daughter, Atiana De La Hoya, 23, was seen walking ahead of Penelope and Alabama in a similar gown.
The celebrations continued with a reception at the historic Castello Brown castle in the hills of Portofino.
Kylie Jenner took to her Instagram Stories to share a series of videos from the party, where fresh cannoli and pasta were served.
After saying “I do” in a white Dolce and Gabbana mini dress with a long embroidered veil, the 43-year-old reality star changed into a lacy black number, complete with a black veil, and headed for the dance floor, where Barker seductively bit off his new wife's garter.
The pair's first dance was to “At Last” by Etta James.
Kourtney – who also has Mason, 12, and Reign, 7, with Disick – and Barker's wedding guests included the bride's mom Kris Jenner and her partner Corey Gamble, sisters Kim Kardashian, Khloe Kardashian, and Kendall Jenner, and her boyfriend Devin Booker.
Barker's best friend Machine Gun Kelly and his fiancée, Megan Fox, and his Blink-182 bandmate Mark Hoppus and his wife Skye also attended.
The couple had recently exchanged vows in a “practise” ceremony in March, before making their union official in a Santa Barbara courthouse last weekend, and then tying the knot in front of family and friends in Portofino.
According to MailOnline, Kourtney entered the garden for the outdoor ceremony at Castello Brown on her mother’s arm, while a woman sang “Ave Maria”.
The couple exchanged vows as dusk fell.