The proposed new location for the branch is at the Spar shop at Knockaraven, Brollagh Road, a short distance away from the current location at 10 Main Street.
The proposal is to create a modern open-plan branch with significantly extended opening hours for customers, said a spokesperson.
Customers and interested parties are being asked to give their comments on the move in a six week public consultation which closes early next year.
Post Office Regional Network Manager for Northern Ireland, Sheila McCann, said: "We understand how important having a Post Office is to residents in Garrison and we are confident that this new modern branch will make it easier for our customers to do business with us and also secure services for the future."
She added: "The proposed changes to the branch are part of a three-year investment programme, the largest in the history of the Post Office, that will see around 6,000 branches, about half the Post Office network, converting to new-style branches. The investment marks a commitment to no more branch closure programmes."
Post Office local is a new concept for delivering Post Office services from an open plan counter with Post Office products and services available alongside retail transactions during shop opening hours, allowing Post Office services to be available for longer offering greater convenience to customers.
Opening hours at the proposed new location will be 08.30 - 21.00 daily, representing an extra 50.5 hours a week to access Post Office products and services.
Customers will be able to carry out a range of Post Office services including cash withdrawal services from partner banks and Post Office card account, access to Post Office Financial and Travel services as well as mail services.
Councillor Brendan Gallagher, from Garrison, said: "I understand that front counter services are to be transferred but we need further clarity about the transfer of postmen and women and where their jobs are going to be. My biggest concern would be that jobs are kept locally for postmen and women."
Sinn Féin MLA Phil Flanagan has urged local people to examine the plans in detail. He said that the proposed relocation will bring a number of concerns about the future delivery of services in the village.
Mr Flanagan said: "The development of this proposal is at an early stage and it is important that all affected people take a closer look at these proposals and how they could impact on the village and the wider community. I would be very concerned that this may be an attempt to further strip back vital services in a deprived rural community and such an approach would not be acceptable to me or the majority of the community.
"I will want some reassurances that this is not the objective behind this proposal and that it will actually improve service delivery in Garrison.
"I know that the extended opening hours will be warmly welcomed, particularly the greater access to cash withdrawals as a fully functioning ATM is something that has been lacking from the village. However, the proposed loss of some services from the Garrison branch will not be welcomed, but it has been stated that these will continue to be available in other nearby branches.
"It is important that the views of the local community are heard on this proposal and I have invited representatives from the Post Office to attend a public meeting in Garrison other first-hand the views of local people."
During the public consultation Post Office Ltd is inviting feedback on any issues customers would like considered before a final decision is taken on the proposal.
The consultation will close on January 4, 2013. Submissions can be made during the consultation by Freepost YOUR COMMENTS to Post Office Ltd, National Consultation Team, Wealdstone Post Office, 1st Floor, Admin, 2 Headstone Drive, Harrow, HA3 5QL, via email to firstname.lastname@example.org, via the Customer Helpline: 08457 22 33 44 or Textphone 08457 22 33 55.