Luke Marshall starts at inside centre alongside Darren Cave with Paddy Wallace named on the bench. Paddy Jackson and Ruan Pienaar continue their half-back partnership.
Full-back Jared Payne will be looking to add to his impressive run of five tries in nine games in the RaboDirect PRO12 so far this season.
Up front for the table-topping province, Tom Court, Rory Best and John Afoa will all start in an unchanged front row.
Second row Dan Tuohy suffered a torn calf muscle against Northampton Saints and his starting place is taken by Neil McComb.
In the other changes to the pack, Nick Williams moves from blindside flanker to number 8 with Roger Wilson dropping to the bench. Robbie Diack will don the number 6 short with captain Chris Henry continuing at openside.
Four players have been called up to the bench - Rob Herring, Adam Macklin, Alan O'Connor and Adam D'Arcy.
If he comes on, the game will be O'Connor's first senior appearance for Ulster. The 20-year-old Dubliner joined the Hughes Insurance Ulster Academy in the summer.
He played his club rugby at Skerries until he was 18 before playing for two years at UCD. He was part of the Leinster sub-Academy before joining Ulster in July.
"I have come up here to play rugby and hopefully I will get a chance tomorrow night. It wouldn't phase me to line out against my home province," he said.
"I just want to perform at senior level - and playing against the European champions is just about as competitive as it gets.
"My dad has tickets for the game and will be making the trip up from Dublin for the match. He is a proud Leinsterman, but I am not sure who he will be cheering for tomorrow night!"
ULSTER (v Leinster): Jared Payne; Andrew Trimble, Darren Cave, Luke Marshall, Craig Gilroy; Paddy Jackson, Ruan Pienaar; Tom Court, Rory Best, John Afoa, Iain Henderson, Neil McComb, Robbie Diack, Chris Henry (capt), Nick Williams.
Replacements: Rob Herring, Callum Black, Adam Macklin, Alan O'Connor, Roger Wilson, Paul Marshall, Paddy Wallace, Adam D'Arcy.