Heidi Klum celebrated her 40th birthday with a hat-themed party on Saturday, marking the first birthday she has spent with her new boyfriend and bodyguard, Martin Kristen, after her divorce from British R&B singer Seal.

Kristen, who has been the model's bodyguard for a number of years, began dating Klum last September, just months after her April 2012 divorce from "Kiss a Rose" singer Seal. The German model was married to Seal for seven years.

Klum and her four children were spotted with Kristen by several reporters as they were picking up breakfast from Starbucks before attending her hat-themed birthday celebration. The couple currently lives in Brentwood, California.

"He's cared for our entire family, mostly for our four children, helped us tremendously," Klum said in an interview with Katie Couric.

"I trust him with my children's life. He's a great man, you know, and we just got to know each other from a completely different side."

Earlier this month, Klum denied claims that the two were engaged, after she was photographed wearing matching Tiffany & Company diamond-and-gold bands that he purchased as gifts.

"I am not engaged. I am not planning to get married anytime soon," Klum said during an interview with OMG! Yahoo.

"It's just a beautiful piece of jewelry ... just something nice."

Klum, who was a Mad Hatter at her birthday party at the swanky Hotel Bel-Air in Los Angeles, was joined by pregnant singer Fergie and other close friends.

On Saturday, the runway superstar posted a picture of a gift her children made for her on Twitter - a glass case with hand sculptures of her their hands.