The individuals arrested are closely connected to gangs based in the Inner Nørrebro neighbourhood of the capital, Copenhagen Police confirmed in a press statement.
A total of 25 addresses across the country, in both Zealand and Jutland, were raided by police with more expected, according to police.
The operation, which was initiated on Tuesday morning, was still on going in the early part of the afternoon.
A comprehensive police investigation targeting the gangs – which have been linked to a wave of gun violence in Copenhagen since the beginning of the summer – led to Tuesday's operation.
It is unlikely to be the last operation of its kind, police said.
“Further actions against the gangs can be expected in the near future,” inspector Flemming Madsen of the Særlig Efterforskning Øst (Special Investigation East) unit said in the press statement.
Several of the arrested individuals are suspected of involvement in shootings and other violent incidents linked to the gang conflict in Copenhagen, which is currently under a reported ceasefire.
Various charges of breaking and entering, theft, fraud and serious violent crime are expected against several of the arrested persons.