After 18 years with longtime boyfriend Keven Undergaro, Maria Menounos is engaged.

The 37-year-old E! host couldn't hide her excitement, revealing the news on her Snapchat moments after her beau popped the question.

The marriage proposal occurred during her appearance on Howard Stern's SiriusXM radio show on Wednesday while she promoting her newly released book, The EveryGirl's Guide To Cooking.

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Time to celebrate: After 18 years with longtime boyfriend Keven Undergaro, Maria Menounos is engaged

Sparkle: The dazzling ring, designed with 220 diamonds, was created by Jean Dousset

According to E! News, the dazzling ring, designed with 220 diamonds, was created by French jeweler Jean Dousset.

Jean told E!: 'Keven chose to add personal elements to the ring by including a Signature Stone hidden underneath. The choice of color and origin of the stone adds thoughtful detail only he and Maria will know and see.'

Keven, who is a director and producer, got down on one knee after Maria wrapped her interview on Howard's show.

He said: 'Literally like the last 17 or 18 years of us fighting [to be] together, and me defending her as best I could...it reminds me just how much I do love you.'

'And although I said that this isn't a proposal, I want to ask you something. Would you make me the happiest man on earth and would you marry me?' he added, as reported by E!

The shocked New York Times best selling author said: 'Are you friggin' kidding me right now? Is this a joke?'

He replied: 'It's not a joke. This I wouldn't joke about. I love you so much and this show's meant so much to both of us...Why not make it official now? Will you honey? Will you accept?'

Maria happily answered: 'Yes, yes, yes! Oh, my gosh! Of course! I can't believe this is happening!'

Shock: The marriage proposal occurred during her appearance on Howard Stern's SiriusXM radio show on Wednesday while she promoting her newly released book, The EveryGirl's Guide To Cooking

Joy: The 37-year-old showed off her toned midriff in a white crop top, which she paired with olive trousers

In love: The reporter styled her dark brunette locks half up and half down, opting for slightly waves tresses

The beauty showed off her toned midriff in a long sleeved white crop top, pairing the piece with olive hued harem trousers.

The reporter styled her dark brunette locks half up and half down, opting for slightly wavy tresses.

For her appearance, Maria wore pink lipstick, smokey brown eye shadow and kohl lined lids for a golden makeup look.

Gushing bride-to-be: Following the surprise proposal, Maria appeared on Jenny McCarthy's SiriusXM radio show to discuss her engagement

Memories: The giddy journalist showed off her sparkling jewelry to the show's host during her appearance

Glowing: For her appearance, the stunner wore pink lipstick, smokey brown eye shadow and kohl lined lids for a golden makeup look

Wedding season: The lovebirds, who first started dating in April 1998, co-founded AfterBuzz TV, an online broadcast network

Following the surprise proposal, Maria appeared on Jenny McCarthy's SiriusXM radio show to discuss her engagement.

Maria looked giddy as she showed off her sparkling jewelry to the show's host during her appearance.

The TV personality shared the news on Snapchat immediately after Keven got down on one knee.

Countdown to wedding begins: Now that she's got the ring, Maria no doubt is already thinking about what kind of wedding she wants

Happy bride-to-be: The TV personality was still giddy with excitement as the couple left the radio station

Partners: The twosome don't need to practice walking down the aisle together - they had that down pretty good on Wednesday

No pre-wedding jitters here: Maria looked more than ready to be married as she showed off more of that gorgeous engagement ring

She held her large diamond ring up for her followers while exclaiming: 'I just got engaged on the Howard Stern show.'

Howard and his co-host Robin Quivers stood in the background smiling as Maria revealed the big news.

The star was still surprised by the proposal and said on Snapchat: 'I am still in shock. My jaw has just dropped. I can't even believe this.'

The lovebirds, who first started dating in April 1998, co-founded AfterBuzz TV, an online broadcast network.

Utter surprise: The E! host couldn't hide her excitement, revealing the news on her Snapchat moments after her beau popped the question