DTH van der Merwe returns to the Glasgow Warriors starting XV. The Canada international winger, who was ruled out for the remainder of the season following shoulder surgery in February, has recovered four weeks ahead of schedule.
The 33-year-old scored the dramatic winning try in Glasgow's last league semi-final victory in 2015, also against Ulster at Scotstoun.
Club co-captain Callum Gibbins returns to lead the side having not played since suffering a head injury against Saracens in March.
Stuart Hogg will play his final game at Scostoun before joining English Premiership side Exeter Chiefs next season, he joins DTH in the backfield, along with fellow club centurion Tommy Seymour.
Sam Johnson and Kyle Steyn start in midfield for the fourth consecutive game while recent recipient of the Guinness PRO14 Young Player of the Season award, Adam Hastings starts at fly-half and Ali Price is once again named at scrum-half.
Robert Harley and Matt Fagerson join Gibbins in the back-row. Jonny Gray returns from illness to start alongside Scott Cummings in the second-row.
It's a full Scotland international front-row, with Jamie Bhatti and Zander Fagerson packing down either side of Fraser Brown.
On the bench, Oli Kebble returns to full fitness to be named in the 23 and Man of the Match against Edinburgh, Tom Gordon is also named amongst the replacements.
Dave Rennie said: "We're in a much better place than we were 12 months ago and have trained with a real edge during this three-week break.
"DTH is back earlier than we expected which is a big boost. His power as well as his experience of knock-out rugby will be invaluable tomorrow night.
"We know Ulster will be a completely different animal to the side we faced here last month and we're going to have to play better than we did that day to get the result.
"We're all determined to a be a part of a Glasgow Final and know we're going to have to play our best rugby of the season to get there."
15 Stuart Hogg
14 Tommy Seymour
13 Kyle Steyn
12 Sam Johnson
11 DTH van der Merwe
10 Adam Hastings
9 Ali Price
1 Jamie Bhatti
2 Fraser Brown
3 Zander Fagerson
4 Scott Cummings
5 Jonny Gray
6 Robert Harley
7 Callum Gibbins (Captain)
8 Matt Fagerson
Substitutes
16 Grant Stewart
17 Oli Kebble
18 D'arcy Rae
19 Ryan Wilson
20 Tom Gordon
21 George Horne
22 Peter Horne
23 Huw Jones
Unavailable players: Bruce Flockhart (shoulder), Chris Fusaro (hamstring), Siua Halanukonuka (shoulder), Nikola Matawalu (knee), Robbie Nairn (thigh), Matt Smith (shoulder), Tim Swinson (ankle) and George Turner (head)