Bronx’s adorable 15-month-old half-sister, Jagger, Ashlee’s mom, Tina and friends were also there for all the fun, which included stops at the Dumbo the Flying Elephant ride.
While Ashlee, 32, rocked a Mickey Mouse hoodie, Bronx wore the park’s must-have birthday badge and appeared to have bought some Disney swag, clutching a shopping bag in a snap shared by his mom on Instagram.
“@Disneyland love love love this place. Magical,” Simpson shared alongside a family portrait with Minnie Mouse.
Ross, 28, also took to social media to share his fun day out.
“My pretty girls! ?I love you!,” he captioned a shot with Simpson and Jagger.
Ross also shared the must-do group shot in front of the Disneyland Railroad and Mickey Mouse lawn.
Simpson isn’t the only celeb hanging out at Disneyland recently.
Nick and Vanessa Lachey were spotted at the park with their kids last month, while Rob Kardashian and Blac Chyna enjoyed a Disney day less than three weeks before Chyna welcomed their baby girl, Dream, on Nov 11.
See more on Rob and Chyna’s Disney day out in the video below.