Hailing from Heradsbygd, he played football in Norway for local club Heradsbygda IL until 2019.[1] He then moved to Wolverhampton, but was not given a chance at Wolverhampton Wanderers after initially going on trial there.[2] In 2022 he made his youth international debut for Norway, playing for Norway U17 against Denmark and Austria.[1]
Hernes made his senior debut for Shrewsbury Town on 30 August 2022, scoring Shrewsbury's consolation goal in a 2–1 defeat to Wolverhampton Wanderers U21 at the New Meadow.[3] On 7 August 2023, Hearnes signed his first professional deal with Shrewsbury Town, keeping him at the club until 2026.[4]