Mullingar man Gilsenan will join forces with Dan Leavy and number 8 Leo Auva'a in a strong back row combination.
John Cooney partners Cathal Marsh at half-back, with Darragh Fanning joining Sam Coghlan Murray and full-back Darren Hudson in a fleet-footed back-three.
If you cannot make it to the Leinster 'A' game on Saturday, you can follow the action wherever you are in the world with ClubApp. Keep up-to-date with every try, kick, scrum and tackle at www.clubapplive.com/leinsterrugby.
Looking ahead to the Donnybrook tie, Leinster 'A' head coach Girvan Dempsey said that the squad are determined to get off to a positive start against Ealing.
"The squad have trained really hard in recent weeks and the attitude of the players has been first class, which will hopefully bode well for the visit of Ealing to Donnybrook," he said.
"The beauty of the British & Irish Cup is that there's an element of the unknown each year in terms of personnel who will be featuring as well as opposition. We have scouted Ealing and they are a strong side - big and hardened up front and a lot of pace out wide.
"We know from experience how difficult (English) Championship sides are and they will benefit from playing week by week.
"But, from our point of view there are a number of players from the Academy, wider senior squad and several club players who will be fired up to make an impression. It should be a competitive game and one which we're all really excited about."
LEINSTER 'A' (v Ealing Trailfinders): Darren Hudson; Sam Coghlan Murray, Tom Farrell, Tom Daly, Darragh Fanning; Cathal Marsh, John Cooney; Jack O'Connell, James Tracy, Royce Burke Flynn, Tadhg Beirne, Ben Marshall, Dan Leavy, Conor Gilsenan (capt), Leo Auva'a.
Replacements: Bryan Byrne, Martin Kelly, Gavin Thornbury, Ross Molony, Luke McGrath, Steve Crosbie, Andrew Boyle.