"It feels surreal," said DJ Jayda G as clubbers returned to the dance floor for the first time since the pandemic began.
About 3,000 people with negative Covid test results attended the Liverpool event on Friday, part of the government's pilot on mass events.
The clubbers did not have to wear face coverings or social distance for the first time since lockdown.
"I went in and I was like, oh my goodness, there are people and they're together and they're dancing and they're smiling and this is actually happening," said Jayda.
"You can feel it, like big energy."
Liverpool University student Elliott Cause, 20, said: "I feel like this is a big moment for the UK. I feel like university students have been struggling without this. I feel like this will do a lot."
Some clubbers said they had "spent a week" choosing outfits for the event at the Bramley-Moore Dock warehouse.
One clubber told BBC Radio 5 live: "We're just excited - we're all on the verge of tears ready to go in.
"It was like coronavirus never happened. It's given me hope for the future."
As the evening wound down, another clubber said: "I thought I had my teenage years robbed from me but after that tonight, it was absolutely amazing.
"I think the main feeling within the crowd was that we feel so privileged to actually have been here - so many students across the country haven't been able to experience this."
Event producer Sam Newson said the industry had been "decimated" in the past year.
"People have moved on - I've got colleagues who have lost houses. It has been incredibly hard, and so to try and get this back up and running is incredibly important."
Liverpool director of public health Matt Ashton said the club event, which will also run on Saturday, was "crucial" for the local economy.
"In Liverpool, it's over 40% of our economic output. So it's really important we start to get the economy opening again."
He said clubbers who test positive in the next five days would be expected to self-isolate and would be spoken to by contact tracers.
Scientists will use data on crowd movements and air quality to see whether people mixing indoors at mass events will increase coronavirus transmission.
The night was part of the Events Research Programme, which will also see crowds return to the FA Cup final and Sunday's music festival in Liverpool's Sefton Park.