And some of Hollywood's biggest names showed up to ring it in.
A source told E! News kids were playing with hula hoops and dancing on the main lawn area in the middle of the property, and played table top football and basketball in another separate area.
The family's strict, low-carb, gluten-free diet was put to the side for the day, with guests dining on hamburgers, fries, and several different salads.
"Chris Martin was walking around the party barefoot, totally relaxed and having a good time," a source told E! News. "He spent a lot of time sitting with Maria Shriver and her kids chatting."
Meanwhile, Gwyneth kept busy with her girlfriends, spending time with Diaz and Stefani.
"Kate Hudson talked to Jon Favreau for awhile," the source said. "Everyone was dressed casually in summer clothes and sunglasses. It looked like a relaxed atmosphere where they could show off their new house and celebrate their son's birthday. People stayed all day and really enjoyed themselves."
Moses (officially) turns seven Monday.