The Hornets started on the front foot as Mario Suarez went close in the early stages with a volley from 20 yards.
However, Woking were back on level terms four minutes later as the ball ended up in the net following a goal-mouth scramble. Charlie Carter was credited with the equaliser.
Just before half time, the visitors almost edged back in front as Etienne Capoue's cross was headed into the path of Suarez, who put another volley wide of the target.
Mazzarri turned to new signing Jerome Sinclair in the second half and the former Liverpool man nearly provided a debut goal when his strike was saved at close range by Poke.
The youngster threatened again soon after when he headed over Ikechi Anya's cross, but Watford were unable to break down a dogged Woking rearguard and were forced to settle for a draw.