It likely depends on what field, and what you're acknowledging them for.
In most medical journals, and as such most journals of "allied" fields like nursing or public health, you must name your funding sources, so institutes and companies take it as assumed that their names will be appearing in publications. One company that's funded projects of mine even provides the boilerplate language in their funding agreement.
If you're acknowledging them for help, or the reasons you'd acknowledge an individual, rather than for funding? Again, likely depends on the field - again, in medicine, many journals consider being in the acknowledgements section to be a tacit approval of the results of the paper, and require you seek permission to put them in the acknowledgements section.
Regardless of whether or not you need to, it's probably decent practice to let them know, especially if they're funding you, because it tells them you're doing productive things with their money.