The arrests were over drug possession with intent to supply, fraud and public nuisance offences.
More than 100,000 people are expected to have attended the three-day event at Glasgow Green by the end of Sunday.
Ambulance Scotland said that 68 people had been treated at the onsite hospital tent for minor injuries and medical complaints.
Police Scotland said it wanted to remind those attending Scotland's newest music festival that officers had a "zero tolerance" approach to drugs.
Two people were also reported to the procurator fiscal for allegedly being in possession of a small quantity of drugs, while 25 people also received a police warning for the same offence.
Ch Insp Simon Jeacocke, event commander for Police Scotland, added: "We continue to have an armed presence outside Glasgow Green for everyone's safety and security."
About 35,000 people attended the Glasgow Green festival on Friday, with 50,000 people watching the bands on Saturday.
Organisers said attendance has exceeded expectations.
The acts on Sunday included 18-year-old Declan McKenna, performing on King Tut's Stage.
Ahead of the show, he said: "I'm feeling good actually, I mean, it's a little more rainy than I was expecting but I'm up for it and looking forward to the show.
"I've never played anywhere other than Glasgow in Scotland, I don't think. The crowds have always been really, really good.
"They have always been really kind to us and very rowdy, to a point. I have got high expectations of Scottish crowds."
Kasabian headlined Saturday night, with the crowd enjoying hits such as You're In Love With A Psycho, Shoot The Runner and Club Foot.
The event runs over the same weekend usually taken up by T in the Park, which organiser DF Concerts announced last November would "take a break" in 2017.
TRNSMT finishes on Sunday, with acts such as The View, local band Twin Atlantic, Two Door Cinema Club and headliners Biffy Clyro.
Eight people have been arrested at the TRNSMT music festival in Glasgow, police have said.