Hanescu, 26, fired 12 aces in the clay-court match at Roy Emerson Arena.
Wawrinka, of Switzerland, is ranked No. 10 in the world, Hanescu No. 80.
Rain forced suspension of the other semifinal, between Spaniard Guillermo Garcia-Lopez and Russian Igor Andreev, after each player won a set.
Andreev won the opening set 7-6 (7-2) and Garcia-Lopez took the second 7-5 before play was halted.