The star plays the role of Jodie Wilde in the Channel 4 soap, having joined in December 2011.
Manning revealed the news on Twitter, saying that Jodie has officially "gone".
Referring to her character's love triangle plot with Texas Longford (Bianca Hendrickse-Spendlove) and Dodger Savage (Danny Mac), she wrote: "Yes Jodie has gone. Seriously Thankyou to everyone for all the #TEXIE love....it was so much fun and loads of love to @hollyoaks!!! :) xx".
The actress had previously toured with Girls Aloud as part of girl group Cookie.
She said earlier this year that she hoped not to sing in Hollyoaks, as she wanted to keep her music and acting career separate.
Ashley Margolis has also revealed that he will leave Hollyoaks as Ricky Campbell after three years.