The Clever Boys entered the game trailing 2-1 from the first leg, and came within an inch of taking the lead after just 10 minutes at the Bidvest Stadium tonight as Gabadinho Mhango did brilliantly on the wing before picking out Siboniso Gaxa, although he could only thump his header against the woodwork.
Thulani Hlatshwayo then had a decent chance after getting on the end of a corner, only to turn his shot wide of the mark, but with 27 minutes gone on the clock, Wits got their goal.
A deliberate handball on the edge of the box gave the Students a great chance to test Seng in the Saint Louisienne goal, although the keeper wasn't even part of the equation as Daine Klate curled home an inch-perfect free-kick to put the hosts ahead on the night and now on aggregate.
Shortly after half-time, Wits put grabbed their second, Sifiso Myeni producing a superb solo run to skip past two defenders before slotting smartly into the back of the net.
With 12 minutes remaining Saint Louisienne, who were playing this match in mourning after the shock death of their club president this morning, struck as Philean managed to pull one back on the night to leave the scores level on aggregate and seemingly set to force extra-time.
However, Wits again showed their tenacity and grabbed the vital goal just four minutes from time, Cuthbert Malajila on the turn before producing a sublime volley to hammer the ball home.
Bidvest Wits: Josephs, Hlatshwayo, Khumalo, Klate (Frosler 67'), Rodgers (Malajila 71'), Hlanti, Mhango, Mlambo, Myeni, Motshwari, Gaxa
Subs: Keet, Frosler, Scott, Pelembe, Pule, Malajila, Keene