Lily Cooper - better known as Lily Allen - has become a mother for the second time after giving birth to a baby girl.
Cooper and her husband Sam are reported to have named her Marnie Rose.
They already have a daughter called Ethel who was born 14 months ago.
Friends and fans have been bombarding the star with congratulations.
Cooper, who now goes under her married name, replied: "Quite overwhelmed by all the well wishing going on. Thank you everybody."
Cooper had a string of chart hits including Smile and The Fear before announcing she was retiring from her pop career.
But after launching a fashion business, she is said to be working on a new album.
When she was asked if she was managing to have a rest after the birth, she responded on Twitter: "Yeah right.
"Can't uncross my eyes. Unique mixture of tiredness and strong painkillers."
According to The Sun, Marnie Rose was born on Tuesday.
Allen seemed to hint that the birth was imminent with an online message earlier this week in which she suggested she was eager to start the labour by tucking into spicy food.
"Third curry this week .... Nothing," she wrote.
She also said her other half was helping with the preparations for the birth, tweeting: "My husband is currently making me a Pantera mix cd to take to the birthing suite."