Before Horan decided to sign with Capitol Records, Cowell highly praised the 22-year-old singer, as reported by The Mirror.
"I think they're all going to do great. Niall is the most loyal. We are expecting to announce something soon with him. I've always known he's loyal," said Cowell as quoted by The Mirror.
Cowell is preparing Horan to become a Justin Bieber style acts. However, as Universal came to offer a better deal and a bigger money, Horan decided to the U.S. to go with Capitol Record.
A source told Daily Star Sunday that the move will come as a real blow to Cowell, who has been talking to Niall for months, wanting him to sign a deal with his label Syco.
"Simon has made no secret of his expectations for Niall to stay loyal to him and has been desperately trying to keep him as a solo act with plans to turn him into a Justin Bieber style artist," the source told The Sun.
"Simon's likely to be so frustrated Niall has gone to a rival."
Cowell is the one who formed One Direction during the "The X Factor" singing competition reality show, aired in the ITV network in 2010.
Horan and four others competed as an individual, but Cowell suggested them to assemble as group. Hence One Direction was born.
One Direction signed with Cowell's label Syco Record for a £2 million ($2.6 million) contract in 2010. After a five years breakthrough success, the group began to fell apart when Zayn Malik left to start his solo career, which he never achieve until now.
The group went on hiatus in December 2015.
After Horan's decision, it is unlikely fans will see One Direction to comeback from hiatus.
