The singer, who already has five-year-old daughter Willow Sage Hart with husband Carey Hart, shared a snap of herself with a huge bump on Twitter, along with the message, "Surprise!"
The 37-year-old looks radiantly beautiful as she poses alongside Willow in the gorgeous photo.
Dressed in a flowing white dress, but maintaining her signature style with a black top hat, Pink, whose real name is Alecia Beth Moore, holds on to her growing belly.
Little Willow looks beautiful in a matching dress as she clings to her mum's arm.
Her fans jumped at the chance to congratulate her, whilst simultaneously expressing their shock at the news.
One said: "queen of surprises", while another commented: "finally some joy in this dismal week. So happy you were able to keep your privacy."