The game continued to be played at blistering pace as a cross from Boyd Curry missed the head of Thomas Boss by inches.
In the 37th minute Sean Lovemore doubled Onehunga's lead with a shot that curled past the outstretched hands of Wanderers keeper Matt Oliver.
In the second half Wanderers began to push Onehunga back in search of a goal, and in the 54th minute their hard work paid off.
Semmy was played through on goal and with delicate ball control, beat keeper Louie Caunter and found the back of the net.
Caunter had to be on his toes again coming out of his box to stop Semmy from levelling the game.
A free kick from Milne in the 78th minute caused problems for the Wanderers backline, as Max Mata connected with the ball but couldn't find the target.
As the minutes ticked down both teams were searching for a goal to settle the game, and it was Wanderers who had the last say.
In the 87th minute, Semmy used his pace to beat the Onehunga defence before powering a shot into the bottom left corner levelling the game at 2-2.
The result of the game had no impact on the table, as Onehunga had been crowned champions in a midweek fixture against East Coast Bays, but Wanderers can take heart from the improved away result.
Wanderers focus will now shift to preparing their summer league squad, with the ISPS Handa Premier League to kick off in mid October.