Inspector Mike Coleman said the number was "not bad, (for) a full moon and a nice hot night," given a typical Saturday night brought about 30 to 40 arrests.
During the gig police arrested nine people at Westpac Stadium and a further six were evicted. Six ambulances were called to assist people with alcohol or drug-related issues.
Earlier in the day police made about 11 arrests after the Wellington Cup races, just over half the previous year's tally.
The drop in arrests has been linked to tighter restrictions on alcohol at the event.
