Heidi Klum & Martin Kirsten: Johan's Birthday Party with Seal!

Heidi Klum keeps it super chic as she heads to a birthday party for her son Johan, 7, at K1 Speed Indoor Go Kart Racing on Saturday afternoon (November 23) in Long Beach, Calif.

The 40-year-old Project Runway host was joined by her boyfriend Martin Kirsten, her ex-hubby Seal, and their kids Leni, 9, Henry, 8, Lou, 4.

PHOTOS: Check out the latest pics of Heidi Klum

The next day, Heidi looked gorgeous on the red carpet at the 2013 American Music Awards, where she served as a presenter.

The week before, Heidi and the family cheered on Johan during his soccer game in Brentwood.

30+ pictures inside of Heidi Klum, Martin Kirsten, Seal, and their kids at the birthday party…