Kelly Osbourne is officially engaged. 

Matthew Mosshart, 29, who has been dating Osbourne, 28, for more than a year, secretly proposed to the E! "Fashion Police" co-host in December and the couple is "really excited" about taking their relationship to the next level, a friend of the reality star revealed.

"Kelly is the happiest she's ever been," a friend of Osbourne told Us Weekly. "Her career is going well, and she's in a healthy relationship with a wonderful guy."

Osbourne and Mosshart met for the first time at her friend Kate Moss' wedding in July of 2011. The couple's relationship was confirmed when they were snapped kissing during a stroll in New York City in December of 2011. In June 2012, the "Dancing with the Stars" alum professed her love for Mosshard on Twitter.

"I'm in love and I don't care who knows about it!" she tweeted.

The daughter of "America's Got Talent" host Sharon Osbourne and rock music legend Ozzy Osbourne confessed recently that when she joined "DWTS" in 2009, she had lost 20 pounds during her stint and lost even more after she left the show. She revealed the secret to her weight loss was being "happy first." 

"People think I lost weight and then got happy, but that's not how it works. You have to get happy first," Osbourne told InTouch. "I made a life change, and the weight loss was an amazing perk.

The 27-year-old also revealed other tips that have helped her maintain a steady 112 lbs., on her 5-foot-2 body frame.

Osbourne is so confident about her new body size that she posed for Cosmopolitan Body U.K. wearing various swimwear. For the first time in her career she flaunted her body in a photo show and it came following a 69 pound weight loss. In one photo, Osbourne is wearing a brown and blue striped bikini with fuchsia-colored lipstick, and in another image she's wearing a ruffled pink bikini showing off her toned stomach and thighs. 

Tags: Kelly Osbourne Fashion Police E!