Herbert reached 8 under through 14 holes Friday, putting himself on pace to break the men's major single-round record of 62 at Royal Birkdale.
A 6-under 28 on the front nine tied the British Open nine-hole mark set by Denis Durnian at Birkdale in 1983, fueled by four birdies in his first five holes.
Jackson Suber, the surprise first-round leader, steadied for a 1-under 69 after three straight bogeys, but that left him struggling to keep pace on a low-scoring day.
Patrick Reed also moved into record territory at 6 under through 14, while Rory McIlroy got back to even par for the championship without matching the leaders' surge.
The scoring push continued a broader trend in majors: Branden Grace first shot 62 in a major at Birkdale in 2017, and four more 62s followed in 2023 and 2024.