Sadie Pilbury, aged 3-weeks-old, is one of two babies who have been chosen to share the part of Hope on the long-running drama.
The newborn will be seen on screen for the first time within the next few weeks when Hope is finally well enough to leave hospital following her premature arrival in December.
Sadie's mother Madeline - who also has a 2-year-old son with partner David - told the Manchester Evening News: "A very good friend of ours works for Northern Kids theatre company and on the day she was born they said Coronation Street was looking for a baby girl.
"We weren't sure at first. We've never done anything like this before - we're not acting people - but when we spoke to the people at Coronation Street we were reassured."
She continued: "They said they usually use twins in case one gets a bit grumbly but they couldn't find any so they're using two little girls instead. They do look quite similar. We've only just filmed the first few scenes.
"Because she's so young there are so many rules and regulations about how many hours she can spend on set - it's just a few hours a day at the most. You're always there with her in case there's a problem but we had no problems at all on the first day, they looked after us so well."
The role of Hope - daughter of troubled Weatherfield couple Fiz and John - has been played by a special-effects doll for her first few weeks on screen.