Thrown by Tobey Maguire's wife Jen Mayer and 90210 actress Sara Foster, the party took place at a private Malibu home and was attended by approximately 60 of Hudson's friends and family members as well as their children.
"It was a family-friendly party with kids of all ages running around. Nicole Richie was there with her kids and they were having a great time playing outside," a source told Us Weekly.
Guests, which also included Courteney Cox and Rachel Zoe, also took part in several baby shower games, including a guessing game for what Hudson and Bellamy's child should be named.
"It was hilarious and got a lot of laughs out of everyone! It was such a fun party - and people stayed for hours," the insider added.
Hudson recently revealed that she and Bellamy, who announced their engagement in April, did not plan the pregnancy.