The showbiz supremo, whose career includes stints on Britain's Got Talent and American Idol, said: "They flooded the market.
"There have just been a ton of shows, and something has simply gone awry."
Cowell, whose US version of the X Factor was axed after falling ratings, said he was treated like "a pariah" after the fall in audience numbers.
He said: "I've had that all my life in the record business. You have a massive hit, then you sign another artist who doesn't hit and it's 'Don't go near Simon. He is so over.' Then you come back with somebody else and you're hot again."
Cowell also said that TV talent shows did not have good records in uncovering successful acts, and judges on shows like the US version of The Voice "sold a ton more records" than the contestants.
He said: "The awful stat is in stars created by these shows."
Leanne Mitchell, who won the first UK series of The Voice, only managed to get to 134 in the album chart with her first release which sold less than 1,000 copies in its first week.
Other talent show flops include X Factor winner James Arthur who was reportedly dumped from Cowell's record label for writing a song about terrorism.
The singer was reportedly dropped by Syco after it emerged his song Follow The Leader included the lyric "I'm gonna blow up your family like I'm a terrorist".