Wellington Harbourmaster Grant Nalder said the ferry departed about 8.15 on Wednesday and hit the southern end of Glasgow wharf.
The ferry was sailing towards the entrance to the channel when the operator Straits NZ made decided the vessel should turn back.
"The company made the decision that they wanted a closer look at the ship so they brought it back into the berth," Nalder told Midday Report.
Nalder said there was "a decent dent" on the hull and a "very small hole" above the waterline.
The risk was low given the size of the hole, its height above the water, and that it was going into a relatively small compartment, he said.
Passengers were able to safely disembark once the ferry returned to port.
Repairs to the vessel were likely to be carried out in the afternoon and the ferry was expected to be back in service on Wednesday evening, Nalder said.
