They were born prematurely at Barnsley Hospital, South Yorks, near Louis' home town of Doncaster, but the babies and their mum are doing fine.
The 22-year-old dashed to be with mum Johanna Poulston, 40, after the latest arrivals on Monday.
Louis already has four younger sisters - Lottie and Felicite and twins, named Phoebe and Daisy.
Johanna has been with the twins' father, Daniel Deakin, 30, for two years. She split from her ex, Mark Tomlinson, as Louis auditioned for X Factor in 2010.
A spokesman for Louis said: "Daniel and Johanna are pleased to welcome twins - a boy Ernest Rupert Atholl Deakin, 5 lbs 12oz, and a girl Doris Poppet Deakin, 4lbs 11oz.
"Daniel and Johanna would like to thank Barnsley hospital, their special care unit, the Embrace team and Jessops special care unit. All the family are delighted."
A source told The Sun: "Louis is over the moon. He met Ernest and Doris and fell in love with them.
"Family is massively important to him so he was made up that he was not abroad and was able to meet them so soon after they were born. His sisters mean the world to him so he's delighted to have two more siblings to spoil."
The happy news comes a month after Louis lost his beloved grandmother Margaret, his stepdad Mark's mum.
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