Alain Giresse's side might have expected a serious test against tournament debutant Madagascar, which topped its group ahead of Nigeria and then upset Democratic Republic of Congo on penalties in the last 16.
But Tunisia was dominant in Cairo, squandering chance after chance before Ferjani Sassi's scruffy strike broke Madagascar's resolve.
There was no sign of a response and instead captain Youssef Msakni soon added to Tunisia's advantage, his goal setting up a comfortable conclusion in which Naim Sliti added a late third ahead of Sunday's semi-final against Senegal.
In an open and entertaining start to the game, Sassi almost broke the deadlock in superb fashion, twisting into space on the edge of the area and firing just over the top.
But further chances did not follow for either side until Wahbi Khazri saw a curling 32nd-minute free-kick touched onto the crossbar by Melvin Adrien.
Tunisia thought it had its breakthrough in the opening minute of the second half, but Khazri strayed offside before controlling Yassine Meriah's lofted pass and scuffing into the net.
It did not have to wait long, though, as Sassi again went for goal from 20 yards and this time benefited from a huge deflection off Thomas Fontaine to wrongfoot the goalkeeper.
Msakni then picked out the bottom-left corner to double Tunisia's lead after Adrien denied Khazri once more, with the victor cruising long before substitute Sliti finished off a 93rd-minute counter to complete the scoring.