Disick, 32, was also joined by a mystery woman. They had a late dinner at Koi restaurant in Soho, and after the meal, Disick exited through a side door.
They then made their way to Up & Down nightclub, where they partied for some time before their next stop, the Soho House in the Meatpacking District.
Kourtney Kardashian's ex, who was wearing a long fur coat ripped at the sleeve, was accompanied by his security.
Kardashian, who was in New York City last week for Kanye West's fashion show, returned to Los Angeles over the weekend and has been spending time with her and Disick's three children.
"There is nothing better than coming home to my little true loves," she captioned a sweet picture on Instagram of a Valentine's Day treat and cards made by Mason, 6, Penelope, 3½, and Reign, 1.
On Tuesday, the Keeping Up with the Kardashians star shared an adorable picture of her and Mason's "beautiful morning" cuddling in bed together.
Kardashian, 36, ended her nine-year relationship with Disick in July after he was photographed cozying up to another woman in Monte Carlo.
Though Disick continued to party for some time after the breakup, he checked into rehab in mid-October and has since completed treatment.
On an appearance on The Ellen DeGeneres Show last month, Kardashian said she and Disick were "getting along" as they co-parent their children and that while Disick will always be family, they aren't back together.
VIDEO: Kourtney Kardashian and Scott Disick Spend Quality Family Time at Home with Kids
Disick then went on Khloé Kardashian's talk show, Kocktails with Khloé, and said many people have the "wrong impression" of him.
"The only thing I'm trying to focus on is calming down and focusing on the kids and trying to be a good dad," he said.
Disick and Kardashian were last spotted together during a friendly shopping trip to a Williams-Sonoma store in Calabasas, California, two weeks ago.