The award-winning singer shared the news with fans on Thursday posting a photo of a pair of tiny socks on Instagram.
“Want to let you all know we've had another beautiful baby girl. We are both so in love with her, and over the moon to be a family of 4,” he said.
Sheeran, the most successful British artist of the past decade, married Seaborn in 2019, having known her since he was 11-years-old.
The couple welcomed their first daughter, Lyra Antarctica Seaborn Sheeran, in August 2020 - with a similar Instagram post with a photo of tiny socks.
Fans were delighted with the surprise news of a second daughter for the couple.
“Congratulations Ed and Cherry,” said one. “Lyra will be the best big sister ever to your little baby girl”.
“Congrats Ed!! Can't wait for the music you make that’s inspired by her,” said another, while a third said: “Seaborn-Sheeran squad keeps on growing, so much love!!”
The music star recently shared a rare photo of him cuddling up to wife Cherry in a hammock on a sunny day to celebrate her 30th birthday.
“HBD to ma baby mama. 30 looks good on you,” he said.
Sheeran has spent a total of 79 weeks at the top of the charts with eight no 1 singles, including the global smash hit Shape of You.
Ed Sheeran - In pictures
He first entered the British charts in 2011 with debut single "The A Team". His most recent success came at the Ivors in London, where he won the category for most performed work with his hit song "Bad Habits".