The former Strictly Come Dancing babe was left with deep laceration on he chin and a fractured left wrist after falling on the way to rehearsals for upcoming West End show 9 To 5: The Musical.
The show, which opens on January 28 at The Savoy Theatre, is based on the music from legendary singer Dolly Parton.
Louise had been cast as one of the lead roles Violet Newstand.
However, the tumble means doctors are now warning her she could miss the show altogether.
After hearing the news, a gutted Amber took to Twitter write: “Well. I leave you for 2 mins.
“Wishing one of my favourite humans the most speedy recovery.
“I can’t wait to be beside you as we play leading ladies together.”
Opening up about the incident, a source said: “It happened on the way to rehearsals on Tuesday morning. She fell in the street.
“She went to hospital and had stitches.
“Then doctors told her she needs time out and can’t do the show.”
They added to The Sun: “She is obviously completely devastated because this is a dream role for her. It doesn’t seem fair.”
Confirming Louise won’t be better in time to make all of the shows, a rep for 9 To 5 said: “We hope Louise will start performances towards the end of March or early April.
“Due to an injury this week, Louise Redknapp has had to temporarily withdraw from performing the role of Violet in 9 to 5 The Musical.
“The recovery time recommended means Louise is no longer able to properly rehearse the show in the remaining time left before opening.
“Together we have made the difficult decision to delay Louise’s start date in the show.”