If your data is regularly spaced you can use WeightedData with Histogram3D. If not you could create your own plot with Cuboid and Graphics3D.
First I'll create some regularly spaced triplet $\{x,y,z\}$ data in dat.
SeedRandom[12345];
With[{hl = HistogramList[RandomVariate[NormalDistribution[0, 1], {500, 2}]]},
dat = MapThread[Append,
{Flatten[Outer[List, Sequence @@ hl[[1, All, 2 ;;]]], 1],
Flatten@hl[[2]]}];
]
dat // Short
{{-3,-(5/2),0},{-3,-2,0},{-3,-(3/2),0},{-3,-1,0},{-3,-(1/2),0},{-3,0,1},
<<156>>,
{7/2,1/2,1},{7/2,1,0},{7/2,3/2,0},{7/2,2,0},{7/2,5/2,0},{7/2,3,0}}
Regularly Spaced Data
With WeightedData each $\{x,y\}$ can be given a weight of $z$. Histogram3D understands this information. All that is needed is to specify bins that match the spacing of the data. In dat both $x$ and $y$ are spaced by $\frac{1}{2}$.
wdat = WeightedData[dat[[All, ;; -2]], dat[[All, -1]]];
Histogram3D[wdat, {{1/2}, {1/2}}]

Triplets in General
For triplets in general you can create your own histogram-like plot using Cuboid and Graphics3D. Here a cuboid is created for each set by taking $\{x,y,0\}$ as the lower corner and $\{x+\Delta,y+\Delta,z\}$ as the upper corner. Deltas, colour, lighting, and the rest I leave to you.
Graphics3D[{Orange, Cuboid[{#1, #2, 0}, {#1 + .2, #2 + .2, #3}] & @@@ dat},
BoxRatios -> {1, 1, 1}, Axes -> True]

Hope this helps.