The 18-year-old winger has joined the Bhoys on an 18-month loan from Manchester City and is immediately eyeing success with the Glasgow giants.
Roberts, who joined City from Fulham for £12million in the summer, will look to take his game to a new level under Ronny Deila as he strives to win plenty of silverware at Parkhead.
"I'm delighted. This is a massive club. As soon as my agent called me and said Celtic were interested, I was jumping at the bit," he told the club's official website.
"Celtic is huge in Scotland and in Europe, and this is what I want. I'm here for a long time and have time to bed-in at the club. It's a long time but I want to be here to develop. I want to do well for Celtic, win trophies and get into Europe. Those are my aims.
"This is the biggest club in Scotland. They play in Europe and a massive stadium like this. I used to wear the kit when I was younger as my mum bought me it and I liked the colour.
"I want to be as successful as anyone else, win trophies and games – I want to get that into my locker for my career.
"I'm very direct and quick. I like to get the fans off their seats, which I hope to do many times, and I like to score goals.
"I have spoken to Ronny a few times and he's been very good with me. I know this is a big club with big players and I know how good they are.
"I just want to keep doing well in training and get a chance to play for this club. I hope to get a chance and make my name from there."