Sofia's Diary started life in Portugal in 2003 as an experiment for the web and mobile internet. The show - about the family life of 17-year-old Sofia Taylor - has more recently been produced by Sony Pictures for social network site Bebo.
Episodes lasting three minutes will air each weekday at 4.55pm from April 28, when the channel takes on its new guise. Fiver will also screen a half-hour omnibus edition every other weekend.
Hannah Barnes, director of programmes for Fiver and Five Life, said it was the first time a UK production had moved from the internet to television.
"I’m thrilled to be working in partnership with Bebo and Sony in what is an exciting broadcasting first in the UK," she said. "Quality programming for 16-24s is booming on the internet, and our decision to showcase Sofia’s Diary shows our commitment to 16-24s, which is part of our wider strategy in building a further connection with this group."
Bebo president Joanna Shields said: "This news represents a milestone for television broadcasting. Fiver's enthusiasm for Sofia's Diary shows that it wants to play a role pioneering the next stage of entertainment."
Fiver has also announced the commission of Generation Sex, a factual entertainment series covering all aspects of sex. Celebrities talking about their exploits will include Joanna Page (Gavin and Stacey), Rebecca Loos, Adele Silva, Paul Kaye and Calum Best.
Barnes said the six-part series was "as contemporary sex a show as you can get".
Several new shows and acquisitions have been announced for the rebranded channel in recent weeks. Fiver will also have a new on-screen look.