Ian Whitten is moved from the left wing to midfield where he will partner captain Paddy Wallace. Stefan Terblanche moves to fill the wing berth vacated by Whitten, meaning Adam D'Arcy earns a recall at full-back.
Paul Marshall and Ruan Pienaar will form the half-back partnership for the second consecutive week, while Craig Gilroy remains on the right wing.
There are fewer changes up front. Chris Henry will travel to Paris with the Ireland squad so Pedrie Wannenburg moves to the lindside of the scrum and Robbie Diack gets a run-out in the number 8 position.
The front five is unchanged from the side that started in the 15-14 win over Ospreys at the Belfast venue last weekend.
With Simon Danielli also ruled out after picking up a hamstring injury against the Ospreys, young backs Luke Marshall and Chris Cochrane are also named among the replacements.
Neil McComb and Mike McComish have been called up to the bench to provide cover in the forwards.
McLaughlin believes a victory would be a massive boost to his side's hopes of reaching the play-offs in May.
"We were in the top four briefly last week and that's where we want to be. We need to be at our best but if we get the win, it will give us something more to build on as were target the PRO12 semis," he said.
"But Edinburgh are a very good team and they are ranked above us in Europe. They've proved how good they are by qualifying for the quarter-finals of the Heineken Cup and they like to play a good style of rugby under Michael Bradley.
"We played very well against them at the turn of the year and we will have to produce something similar at Ravenhill.
"For us, the 20-minute period after half-time will be crucial. That's when we have to step it up and keep improving through to the end of the match."
McLaughlin is disappointed that the names of Spence and Danielli have been added to a growing injury list, but insists it will provide opportunities for others to stake a claim.
"We have a bit of a break after this game, so we are hoping to have quite a few of the injured players back for the match against Treviso later this month."
The Ulster boss is delighted to be playing at Ravenhill on consecutive weekends, where his side have lost only once in their last 18 matches.
"The players get a huge lift from playing in front of their home crowd and there is no doubt it has a positive effect on results. As always, we are determined to produce a performance for the fans and hopefully get the result," he added.
There are still tickets available for Friday's game. They can be bought online at www.ulsterrugby.com or by calling the ticket office on 02890493222 (ticketing option). Alternatively, you can pay at the gate on match night.
Ulster Rugby are appealing to supporters to be mindful of local residents and to avoid parking in the immediate vicinity of the Ravenhill grounds on match nights.
Fans are encouraged to make use of the complimentary Park'n'Ride facilities on Ulster Rugby matchdays located at Pirrie Park on the Ravenhill side of the ground, and along Montgomery Road, on the Mount Merrion side of the ground.
ULSTER (v Edinburgh): Adam D'Arcy; Craig Gilroy, Ian Whitten, Paddy Wallace (capt), Stefan Terblanche; Ruan Pienaar, Paul Marshall; Paddy McAllister, Andi Kyriacou, John Afoa, Lewis Stevenson, Dan Tuohy, Pedrie Wannenburg, Willie Faloon, Robbie Diack.
Replacements: Nigel Brady, Callum Black, Adam Macklin, Neil McComb, Mike McComish, Ian Humphreys, Luke Marshall, Chris Cochrane.