The 22-year-old was arguably man of the match for his country in the 2-0 defeat to Germany at Windsor Park, making a string of saves to keep his side in the game.
"He played very well," O'Neill said of his Peacock-Farrell's performance against Germany.
"He's a young goalkeeper with not a lot of experience either at international level or in first-team football.
"He's not had any first-team minutes for six months so I was pleased with him.
"He knows himself his kicking could have been better but it was a big night with some big saves at an important part of the game.
"He's going to be a big goalkeeper going forward and hopefully we see him playing first-team football soon.
"It's difficult to come in and play games of this nature consistently when you're not playing first-team football."