Police confirmed 21 men and 10 women were dealt with for a series of "minor public order offences" during the concert at Bellahouston Park.
The 31 people were either reported to the procurator fiscal or issued with a fixed penalty notice. No one was taken into custody.
Superstar DJ David Guetta headlined theSouth Side event on Saturday night. He was supported by Swedish dance sensation Steve Angello.
American indie stars The Killers will be the main act at the final show tomorrow.
More than 100,000 fans are expected to have attended the outdoor gigs.