Bosses blamed a drop in use of more than a third over the last five years for the decision to shut the Cockermouth premises.
The nearest HSBC branches will be in Workington and Whitehaven.
HSBC has written to customers about the closure.
It said an alternative counter service would be available at the post office, with free cash withdrawals available for current account holders.
The bank is offering customers one-to-one meetings to discuss the closure.
A spokesman said 93 per cent of contact with the banks was now done by phone or online, with 97 per cent of cash withdrawals from ATMs.
The branch’s two staff will be able to relocate to other local branches, he said.
Waugh & Musgrave, the firm of solicitors based above the bank, is unaffected by the closure.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here