Championship side Swansea will host supporters for their semi-final home leg against Barnsley on 22 May.
League Two Newport County will also welcome fans to Rodney Parade for the visit of Forest Green Rovers on 18 May.
The games will mark the first time supporters have been able to return to stadiums in Wales since coronavirus restrictions began in March 2020.
The play-off fixtures are part of a series of test events, the plans for which were announced by First Minister Mark Drakeford last month.
No firm decisions could be taken before the results of last week’s Senedd elections, although it is thought fixtures had already been earmarked before the election period.
A list of nine pilots have now been confirmed, including Wales’ football friendly fixture with Albania at Cardiff City Stadium on 5 June which will be set to welcome 4,000 supporters in the side’s final game before this summer’s European Championship.
Up to 1,000 fans will also be able to attend the four-day County Championship fixture between Glamorgan and Lancashire at Sophia Gardens that starts on 3 June, while the Wales Triathlon in Fishguard on 11 and 12 June will also be open to registered participants.
Glamorgan chief executive Hugh Morris said: “We are absolutely delighted members will be allowed back into Sophia Gardens and able to cheer on the team.
“We are grateful to the Welsh Government for selecting us as a test event and we will work closely with them, as well as other key stakeholders… to help prepare for the pilot.”
Cultural events – including theatres – and business are also included in the first tranche of pilots with more to follow over the summer, should they prove to be successful.
Not originally on the list, talks with the EFL to include the play-off games began after Swansea City secured a top-six finish a fortnight ago, with Newport confirming their place at the weekend.
The EFL say Swansea and Newport will determine with local safety advisory groups the exact number of supporters that will be able to attend each game, with the clubs making ticketing announcements in due course.