A 16-year-old boy has been charged with murdering Tom Webb, from Alvaston, on 19 January.
The 22-year-old died in hospital after being stabbed once on St Peter's Street, Derbyshire Police said.
Two 15-year-olds and two 16-year-olds have been arrested along with a 14-year-old,  a 17-year-old and 18-year-old, police said.
The 16-year-old charged with murder, who cannot be named for legal reasons, was remanded in custody after appearing in Nottingham Crown Court.
Police said the arrests of the seven, all male, were made after the force made an appeal for members of a group that were seen leaving McDonald's on the evening of the stabbing to contact them.
One of the 16-year-olds arrested on suspicion of violent disorder remains in police custody, while the others have been released on bail pending further inquiries.
Detective Chief Inspector Dave Cox, who is leading the investigation, said: "We have made a number of arrests in connection with this crime but we are still keen to speak to anyone who might have information."
Mr Webb died in hospital after being found in St Peter's Street on Tuesday evening.
Seven people have been arrested on suspicion of violent disorder after a fatal stabbing on a street in Derby.