Police were called to the Galleria, at the junction of Bon Accord Street and Langstane Place, at 00:10 on Friday.
The man who died has been named as Craig Grant, from Aberdeenshire.
Police Scotland said three men - two aged 32 and one aged 21 - had been arrested in connection with the death.
Officers earlier urged people to come forward if they had mobile phone footage of the incident.
Ch Insp Richard Craig had said: "We are aware that this area would have been busy at the time with a number of people in the area.
"We are appealing for anyone who may have seen the incident to come forward. We are also aware that people may have captured the incident or the aftermath of it on their mobile phones and we would urgently appeal for them to come forward as soon as possible.
"An inquiry team has been set up involving divisional and specialist resources to establish the full circumstances surrounding the death.
"We would like to thank the community for being patient while police carry out enquiries in the area."
Three men have been arrested after a 26-year-old man died in Aberdeen city centre.