The online drama will mark Helen Flanagan's return to the show, after the actress took time off from the role as the eldest Webster.
The 20-year-old, who went peroxide blonde during her break, returned to filming this week after having her cropped locks dyed brunette again.
A special Rosie Webster Twitter account and new website will also be launched. Viewers will see the ambitious model discuss her plans on the parent series. Rosie will also take boyfriend Jason Grimshaw to London to appear on Lorraine Kelly's daytime show.
The online spinoff will follow Rosie's exploits as she becomes an internet sensation following a scrap with a rival model on Lorraine, an appearance on Loose Women and interview with Capital FM's Jonny Vaughan and Lisa Snowdon.
"This is a great opportunity for fans of Coronation Street to watch extra exclusive content on ITV.com that links back into the main show on ITV1," a show spokesperson said.
The ITV production follows previous online successes such as Gary's Army Diaries and Ken and Deirdre's Bedtime Stories.
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