[5] As an amateur fighter, Herbert competed at welterweight and didn't consider the strain of a weight cut to be worthwhile at such a level.
He recorded consecutive second-round knockouts with Full Contact Contender and later signed a four-fight contract with BAMMA.
[8] On 14 November 2015, Herbert made his promotional debut at BAMMA 23 and beat Ben Bennett via knockout in the second round.
On 16 December, he suffered his first loss against future UFC fighter Rhys McKee in a lightweight title bout at BAMMA 27.
[citation needed] In February 2017, Herbert was due to face Steve Owens at BAMMA 28, but his opponent was forced to withdraw with illness the day before.
He was then due to fight Donovan Desmae at Cage Warriors 98, but had to withdraw two weeks prior to the bout.
On 2 March 2019, Herbert appeared in the co-main event at Cage Warriors 102 and beat Steve O'Keefe via a first round knockout.
He was then handed his first title opportunity with the promotion and beat Jack Grant at Cage Warriors 106 to claim the vacant lightweight championship.
[22] After a point deduction in the third round due to multiple groin strikes, the fight ended in a majority draw.