Dan and Seb will get equal treatment
Ricciardo will partner three-time World Champion Sebastian Vettel at Milton Keynes from 2014 after he was confirmed as the retiring Mark Webber's replacement earlier this week.
However, don't expect the 24-year-old to take a backseat to Vettel as the team are promising to give them equal treatment.
"The decision to take a junior driver doesn't mean anything changes," Horner said. "Both drivers will get the same opportunity and the same equipment, but inevitably there will be a natural pecking order determined by the driver who is in front on track. Sebastian has won a lot of races and is a multiple World Champion, so with that comes a lot of expectation. But the reality is that both drivers, as has always been the case, will get identical opportunity and equipment."
He added that Ricciardo is a lot quicker than a lot of people give him credit for.
"Daniel is very quick and we know he's very quick and Sebastian is the best in the business at the moment. It's very tough to be his [Vettel's] team-mate so it will be a big surprise for him. But I think people are going to be surprised at the pace that Daniel does have. We've seen it at the simulator and at track tests, and we've seen flashes in the Toro Rosso.
"I think he really does have a natural ability. He's a good personality, a good guy to work with and I've never seen him yet without a smile on his face. For sure, now he will be smiling from ear to ear."
The Australian came through the ranks of the Red Bull Junior Team and he first got a taste of the F1 action when he was loaned out to HRT for the latter half of the 2011 season.
He stepped up to the Toro Rosso seat in 2012 and has picked up 22 points in his 41 races for the team with is best finish a P7 at this year's Chinese Grand Prix.
Horner, though, concedes they won't expect too much from him in his first year as it will be a learning curve, but they do expect him to challenge in the long term.
"My expectations of Daniel next season are that he will continue to improve," he said. "He's a young driver, he's inevitably going to make a few mistakes early on but he will learn from them and improve. This is very much a medium- and long-term view that we are taking in developing him. Of the current crop of youngsters he is genuinely an exciting prospect