Youtube! Mariah Carey�s black bikini toned in a new commercial for Jenny

She's lost more than 30 pounds since the April birth of her twins, and it shows: Mariah Carey looks amazing.

The 41-year-old singer is confident enough about her newly slender self to flaunt her stomach in a new advert for her weight loss system, Jenny (formerly Jenny Craig).

She appears in a black bandeau top and sultry black skirt with thigh-high slits in the advertisement.

Scroll down to watch the commercial...

Mariah is on fire! Mariah Carey shows off her 30lb. weight loss in a new commercial for Jenny

She sings a new version of her 1991 pop hit, Make It Happen, while Jenny users announce how much weight they've lost on the programme.

Mariah, who urged her Twitter followers to watch the new commercial today, announced her role as the company's Brand Ambassador back in November.

She had gained 30 pounds after the April birth of twins Moroccan Scott and Monroe and felt pressure from the media to shed the weight quickly.

Ecstatic about her weight loss! Since giving birth to twins this April, the singer has shed 70lbs.

Toned tummy! The Make It Happen singer has whittled her waistline

Non-thunderous thighs! Mariah shows off her toned thigh and a little leg

She told ABC News: 'If they want to rag at me for looking like a huge boat, like that wasn't my fault, I couldn't help it.'

'Carrying two human lives inside me and doing the best I could. What am I going to do?'

Bold move! The new mother is confident enough to expose her body

Singing for her supper! Mariah is the brand ambassador for Jenny

Strike a pose! The All I Want For Christmas Is You singer poses in a tiny tube top

She started using the Jenny system herself in July; she credits the programme for 30 pounds of her weight loss and 40 pounds to the water weight she shed from her pregnancy.

'I'm proud of how hard I worked to get my body back,' she said on OWN's Rosie Show. 'I had to do this for me.'

Tweet your heart out! Mariah tells her Twitter followers to watch her latest commercial

She discussed her reasons for signing on with the company in a statement.

The All I Want For Christmas Is You singer said: 'As an artist, I use my voice to entertain. But, today I want to use my voice to draw attention to a serious matter.'

'Two-thirds of the country is placing themselves at risk for heart disease and diabetes. Largely, that is due to unhealthy eating patterns and lack of physical activity.'

Slimline! Mariah stepped out in Aspen in a skintight ski outfit that showed off her slender frame

She finished: 'I obtained a greater understanding of this when I was pregnant with my twins and dealing with my own health issues. That's why I feel so strongly about working with Jenny and the American Heart Association to help Americans get serious about their health as it pertains to these issues which are so important.'

She has recently showed off the results of her weight loss by wearing a figure-hugging spandex ski suit while celebrating the Christmas holiday with husband Nick Cannon in Aspen.