"I'm over the moon to tell you that on Sunday Jesse proposed and I happened to say Yes. ❤," the new mum wrote on her Twitter page on Thursday night.
The 32-year-old received warm congratulations after sharing the news with her 4.8million followers on the social media site.
Celebrity Juice team leader Fearne and guitarist Jesse are parents to ten-month-old son Rex Rayne.
Fearne hinted at her desire to tie the knot in an interview with Cosmopolitan in September.
"I'd love to get married and I'm sure Jesse would too, but we don't have any plans yet – we're so hectic with a baby and two other kids [Jesse's two children Arthur, 11, and Lola, seven], and we're both working," she said. "I think it's important to feel like a family unit though."