The 21-year-old England Under-21 international joins the Claret and Blue as a versatile asset who can play at both centre-back and left-back.
Humphreys made his debut for Chelsea in the FA Cup against Manchester City in January 2023 but has failed to book his place in the first team ever since.
Last season saw him on loan at Swansea City where he made 26 appearances, and scored one goal. He feels like Burnley is a huge step up and he cannot wait to get started.
"Burnley is a club with huge ambitions, the owners know what they are doing, and they really want to push the club on as much as possible.
"It makes so much sense for the next step in my career. I had really good conversations with him (manager Scott Parker) and that is always pivotal when it comes to transfers.
"It was completely perfect, everything he was saying to me. He knew about my game; he wants to work with me and help me improve. That is all you want to hear as a player."