The journalist vowed to beat his competitors Fox News and MSNBC in the ratings when he replaced longtime CNN anchor Larry King in January 2011, but has now acknowledged that the programme's viewership could be better.
"It isn't as successful as I'd like it to be. I'd like to get the ratings significantly higher, and we believe there is a real opportunity this year to put the foot on the gas," Morgan told The AP.
He added: "Am I pleased with where we ended up after the first year? Yeah, actually, I am. It would be pretty churlish to be overly critical given that we've taken the ratings up [over King's final months]."
Morgan also defended his decision to largely abandon King's trademark live interviews for taped chats.
"I always think if you've been recruited based on a particular thing that you're doing, you tinker with that at your own peril," the presented noted. "Anchoring a live news programme wasn't something I'd done before. I wasn't sure I'd be good at it."
Piers Morgan Tonight celebrates its first year on the air all this week with interviews with Chelsea Handler, Rosie O'Donnell and former US President Jimmy Carter.
The series airs weeknights at 9pm ET on CNN and at 8pm UK time on CNN.
Morgan recently quit America's Got Talent to devote more time to Piers Morgan Tonight. He has been replaced on AGT's judging panel by controversial radio host Howard Stern.
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