The only change up front sees Declan Fitzpatrick replace John Afoa in the front row where he is joined by hooker Rob Herring and Callum Black.
Team captain Johann Muller and Lewis Stevenson continue their partnership in the second row, while the loose forward trio of Sean Doyle, Robbie Diack and Nick Williams will be hoping to maintain their impressive form from last weekend.
With Paddy Jackson still not fully recovered from his calf injury, Niall O'Connor will start at out-half with Michael Heaney retaining the number 9 jersey.
Darren Cave has been promoted from the bench to start at outside centre at the expense of Chris Farrell. Luke Marshall, Michael Allen, Craig Gilroy and Jared Payne complete the starting back-line.
Mark Anscombe is delighted to welcome back Ferris and Trimble into his matchday squad, saying: "When you bring players of that calibre back into the mix it gives everyone a lift.
"The two boys haven't played much rugby in a while so you have to put that in perspective and not expect too much from them this early. Putting them on the bench is a good way of easing them back in."
Explaining the changes to his starting team, he commented: "With Paddy Jackson it was a precaution with his calf, he's not 100% but he's feeling much better than he was and he's progressing well. It wasn't worth the risk and we wanted to give Niall another chance to show what he can do.
"Darren Cave was on the bench last week, he's been training with the team now for a few weeks and I thought he came on for the last quarter of an hour last week and added greatly to the team.
"He's an international so he brings that experience to a youthful back-line. Declan is the same, he's been training well and we wanted to have a look at him from the start."
Anscombe continued: "There are a lot of areas to improve on but you would expect that and the main thing is that we're progressing.
"Over the next few weeks we'll keep integrating players back into the team and that will allow us to keep developing and growing our game. It's early days and we've just got to keep our feet on the ground and know where we're at."
ULSTER (v Ospreys): Jared Payne; Craig Gilroy, Darren Cave, Luke Marshall, Michael Allen; Niall O'Connor, Michael Heaney; Callum Black, Rob Herring, Declan Fitzpatrick, Johann Muller (capt), Lewis Stevenson, Robbie Diack, Sean Doyle, Nick Williams.
Replacements: Nigel Brady, Tom Court, John Afoa, Neil McComb, Stephen Ferris, Paul Marshall, Paddy Jackson, Andrew Trimble.