Detective Senior Sergeant Mark Stringer said most bikies left by midnight and a few revelled until five or six on Sunday morning.
He said the 30 or 40 members who showed up were generally “fairly quiet and well behaved”.
The Darwin chapter opened about a year ago and is low on numbers. Many at the party were out-of-towners.
Sen Sgt Stringer, from the Organised Crime Division, said extra police were put on to watch the festivities.
Police also made contingency plans for members kicking on to Mitchell St but there were no reports of trouble.
“Generally their hierarchy tells them not to,” Sen Sgt Stringer said.
“If they’re wearing their gear they can’t get into the pubs anyway, plus they’re a bit of a magnet for some of the other dickheads in town who make a smart comment or want to show how tough they are, then the next thing they know there’s 10 bikies kicking their head in.
“That sort of thing has happened in the past but not this time.”
Bikie gangs the Rebels and Hells Angels have long been established in Darwin.
Sen Sgt Stringer said bikie gangs were now often internally divided.
“You’ve got guys that still ride bikes and are a bit older and a bit more sensible, then you’ve got a bunch of young dickheads like we’ve got here with the Rebels, who don’t even own a bike, don’t even have a licence and can’t even ride a bike,” he said.
“It’s supposed to be about a motorcycle club, that’s what they’re telling everyone ... most of the guys who came up this time looked like they were older guys who are interested in bikes.”
Bandidos’ Australian boss Jason Addison told the NT News last year: “We are against drugs. It’s in our constitution about drugs. And for anybody to say that’s the reason we’re moving to town, it’s a load of s …, or else we would have been there 25 years ago.
“We are no trouble to the community at all. People don’t have to fear us in any way, shape or form.”