Three others arrested in the probe on suspicion of incitement to murder have been released but are still the subject of investigation, prosecutor Andreas Nyberg said.
The man to be held in pre-trial detention was in his 20s and had been in police custody since Thursday, the prosecutor said.
No date has yet been released for his court hearing.
Three men aged 15 to 20 were killed late on Tuesday in broad daylight at a hair salon in central Uppsala, a university town north of the capital, Stockholm.
The shooting has fuelled fears among some people in Sweden of a rising tide of gang violence, although police have not confirmed that the shooting was gang-related.
According to the Swedish press, at least one of the victims had ties to organised crime. Police have not confirmed that claim.
Sweden has been seeking in recent years to stem a wave of violence between rival gangs vying for control of the drug trade.
Uppsala has long been the base of Sweden’s two most notorious rival gang leaders, Ismail Abdo and Rawa Majid, although both are suspected of orchestrating their operations from abroad. (AFP)
