Dates and times for these fixtures will be announced in due course
Shelbourne will host Crystal Palace in the league phase of the Conference League.
Joey O'Brien's side's other home games will be against Kosovo's Drita, and Hacken of Sweden.
While their away fixtures will see the Reds face Shkendija in Macedonia, Slovenia's Celje and Dutch club AZ Alkmaar.
Shamrock Rovers matches in Tallaght will be against Shakhtar Donetsk, Celje and Malta's Hamrun Spartans.
The Hoops will travel to Sparta Prague, AEK Athens of Greece and Iceland's Breidablik.
Dates and times for these fixtures will be announced in due course.

All Ireland Football Championship Opening Round Fixtures Confirmed
Tommy O'Brien Among Injury Doubts For Leinster's Champion Cup Final On Saturday
Monday Morning Sports Update
Sunday Evening Sports Update
Mourinho's Benefica Go Unbeaten but Miss Title
Brave Kildare Fall Short in Leinster Ladies Final
Chelsea Appoint Xabi Alonso as New Manager
Conor McGregor Set for UFC Return in July