The Colwyn Bay branch will close on August 15, 2023.
Posters will be displayed in the branch giving details of the closure, and HSBC will be writing to regular users of the branch on 23 January 2023 to provide more information about the closure, and the alternative services available to them.
Mr Millar said: “I am extremely disappointed to see HSBC abandoning our high streets in this way with total disregard for their customers and staff, and I am particularly concerned that Colwyn Bay is to lose another bank – having seen the closure of Barclays Bank only two months ago. Customers will have to travel over seven miles away to Llandudno if they want to see someone face-to-face - and who knows how long that branch will be open for!
“Whilst I recognise that more people are now banking online, there are still many people, particularly the elderly, who like to bank in person and it is a great worry that this option is being take away from them.
“Bank closures have been commonplace in recent years and I have repeatedly raised my concerns about this in the Senedd chamber. They impact on businesses and the whole community in general.
“As I have previously said, we really need to see a long term plan to secure banking services in local communities so that everyone can access face to face services close to where they live. Sharing premises, the development of partnerships with other firms, and mobile banking services may help to achieve this aim.
“I will be writing to HSBC to express my strong objections to these plans.”
It comes as HSBC has announced that it will be closing 114 branches in 2023.
The move comes as the bank shares that more people are choosing online banking over using a physical branch to do their banking.
HSBC found that the number of people visiting has dropped by 65% over the course of five years.
In a statement from the bank, it said: "The decline in branch use has accelerated so much since the Covid-19 pandemic that some of the branches closing are now serving fewer than 250 customers a week."
Jackie Uhi, HSBC UK managing director of UK distribution, said: "People are changing the way they bank and footfall in many branches is at an all-time low, with no signs of it returning.
"The decision to close a branch is never easy or taken lightly, especially if we are the last branch in an area, so we’ve invested heavily in our ‘post closure’ strategy, including providing free tablet devices to selected branch customers who do not already have a device to bank digitally, alongside one-to-one coaching to help them migrate to digital banking."