Addison is named at fullback and is one of five changes to the starting team who recorded a bonus point win over the Isuzu Southern Kings last time out.
Addison will be joined in the back three by Louis Ludik and Craig Gilroy - Ulster’s current most-capped player who will make his 172nd appearance. James Hume returns to partner Luke Marshall in midfield.
John Cooney starts at scrum-half and will be one step closer to his 50th cap milestone, making his 49th appearance. He will play alongside Billy Burns at fly-half, who will captain Ulster for the first time in a competitive game.
There are three changes in the pack; Jack McGrath returns to start at loose-head, along with John Andrew at hooker and Tom O’Toole anchoring the tighthead position. Kieran Treadwell comes in to join the PRO14’s top tackler in Round 3, Alan O’Connor, in the second row.
The back row remains unchanged with Matthew Rea at blindside flanker, Sean Reidy at openside, and Marcell Coetzee at number 8.
Nick Timoney has completed his recovery from a hand injury sustained in pre-season and is available off the bench, along with fellow forwards Adam McBurney, Eric O’Sullivan, Ross Kane and Sam Carter. David Shanahan, Bill Johnston and Matt Faddes make up the backline replacements.
Ulster team to play Cardiff Blues, Guinness PRO14 Round 4, Friday 25 October 2019 at Kingspan Stadium (kick-off 7.35pm):
(15-9) Will Addison, Craig Gilroy, Luke Marshall, James Hume, Louis Ludik, Billy Burns (Capt.), John Cooney;
(1-8) Jack McGrath, John Andrew, Tom O’Toole, Alan O’Connor, Kieran Treadwell, Matthew Rea, Sean Reidy, Marcell Coetzee.
Replacements (16-23) Adam McBurney, Eric O’Sullivan, Ross Kane, Sam Carter, Nick Timoney, David Shanahan, Bill Johnston, Matt Faddes.
Tickets for the game, priced from £17 for adults, £12 for juniors, and £46 for a family of four, are still available at ulsterrugby.com/buytickets