Piutau had routine ankle surgery on Tuesday and is expected to return to training within eight weeks.
The New Zealander will miss Ulster's game against the Barbarians on 1 June and will not turn out for the Baa-Baas three days earlier against England.
Olding underwent an ankle operation and Herbst had surgery on a knee problem.
Centre Olding had been carried off injured during the second half of Ulster's defeat by the Ospreys at the Liberty Stadium on 29 April.
Ulster players Charles Piutau, Stuart Olding and Wiehahn Herbst are set to be fit for the start of next season after undergoing successful surgery.