Pudsey the dancing dog and his partner Ashleigh stole the show in the first live Britain's Got Talent semi-final, flying straight into the final.
The pair won over all the judges and topped the public vote after pulling off a routine reminiscent of a scene from The Artist.
Cowell told the dancing duo:
This is what I have been waiting for all my life. I have had a lot of dogs in my life but never one like this.
This is what this show is all about - I loved it, love you.
After hearing the result 17-year-old Ashleigh from Northamptonshire said:
I promise me and Pudsey are going to come back and we're going to blow you away.
Welsh male choir Only Boys Aloud were also jubilant after their higher tally of votes took them through to the final when the judges were split.
But Manchester boy band The Mend were sent home disappointed after losing out to the 140-strong choir - vowing, however, to "keep going 100%".
Twelve-year-old Lauren Thalia from Hampshire won rapturous applause with her soulful guitar performance, but it was not enough to see her through to the next stage.
Also in the semi-final, Zipparah Tafari from Manchester was forced to explain his lyrics about his phone and his keys to a curious Cowell; Essex six-piece Jive Aces dazzled in yellow as they gave the Bare Necessities their all; London hip hop dance act United We Stand got the thumbs down from the judges; R&B singer Rachel Knowland from Kent rolled back the years singing Be My Baby; and Analiza Ching, from Beaconsfield via China, gave an energetic violin performance.
But all were booted out when the phone lines closed. The second live semi-final is on ITV1 tonight at 7.30pm.