Doors to the event at Glasgow Green will open at 14:00.
TRNSMT is being held on what was traditionally the weekend of the T in the Park festival, which is not taking place this year.
Other bands appearing over the weekend include include Kasabian, Biffy Clyro and The Kooks.
The acts will play across three stages at Scotland's newest music festival, with highlights being broadcast every evening on a BBC Scotland programme presented by Edith Bowman.
Radiohead will headline the opening night, with Kasabian headlining on Saturday and Biffy Clyro closing the festival on Sunday.
Organisers DF Concerts announced TRNSMT in January, two months after saying it was suspending T in the Park to "take stock" of a challenging two years since the festival moved to Strathallan from Balado.
The promoter said "continued restrictions" had had a "negative impact" on festival-goers.
T in the Park's first year at Strathallan in 2015 was plagued by traffic problems.
Two teenagers died at the 2016 festival in separate incidents, while witnesses reported fights and illicit drug use in the campsite area.
Police Scotland said on Wednesday that security would be tight at TRNSMT following the recent terror attacks in Manchester and London, with armed police patrolling near the venue and bag searchers being carried out on festival-goers.
Officers also warned there would be a zero-tolerance approach to drug-taking and anyone found with illegal substances would be arrested.
Flares, smoke devices and other pyrotechnics are banned from the festival area and anyone who is drunk will not be allowed entry.
The three-day TRNSMT music festival in Glasgow is to start later with a Friday line-up of acts including Radiohead and Belle and Sebastian.