David Walliams, Amanda Holden, Alesha Dixon and hosts Ant & Dec will also be back to find a new British variety star.
"I loved doing the show last year, the new panel worked really well and I'm very happy they have all agreed to come back," said Cowell.
"Last year was a special year for talent and I hope that in 2013, off the back of an amazing year for Britain, we find another global star."
Comic star and fellow judge Walliams joked: "My Simon and I are going to be together again. I'm delighted to confirm I will be a judge on Britain's Got Talent again next year. I am so happy I could cry."
Ashleigh and Pudsey became the first animal act to win the ITV talent show last year and have gone on to become stars around the world, appearing on The Tonight Show with Jay Leno, starring in panto together and even releasing their own 'autobiodography'.
Host Dec said: "Simon was the happiest I have ever seen him when Ashleigh and Pudsey won! I'm not sure we'll ever see him as happy again – so that's the challenge Great Britain, show us what you've got!"
Ant joked: "You think you've seen it all then a man with a saucepan on his head turns up! We can't wait to see who or what turns up this time."
Last year's series also produced opera duo Jonathan & Charlotte, male choir Only Boys Aloud and pop trio Loveable Rogues, who are currently finishing their debut album.
The show is open to acts of any age, background or talent and the main auditions start in January. The panel will visit Cardiff, London, Glasgow, Manchester and Birmingham to find the UK's next big superstar.
A new twist to this year's show is that members of the public can act as 'Star Scouts' and recommend unsigned talent for the show. If a Star Scout finds the winning act, they will be given £10,000.
Britain's Got Talent will return to screens in the spring.