The closure, which will be intermittent, begins on Monday, January 7, and runs from 9am to 4pm, with the bridge fully open at weekends.
Pedestrians and cyclists will continue to be able to use the bridge but may face short delays at times until it is safe to cross.
To minimise the impact, and because of the nature of the works, there may be periods during this time when the road is open to all traffic and diversion and advance warning signs will notify drivers of this.
A fully-signed diversion route will be in place for the duration of the closure, which will allow the development activities to support the second round Heritage Lottery Fund (HLF) bid to take place, including chamber inspections to the English and Scottish towers and painting works.
The works are required as part of aproject to conserve the historic bridge, near Horncliffe, which secured a £360,000 development grant from the HLF last year.
It meant the £7.3million project could be progressed further, ahead of a second round bid submission planned in March 2019.
Scottish Borders Council, Northumberland County Council, the Friends of the Union Chain Bridge and Museums Northumberland – formerly known as the Woodhorn Charitable Trust – are working on the scheme.
A spokesman for project partners said: “We realise this is a lengthy daytime closure but it is absolutely essential that we undertake further detailed investigations into the condition of the bridge and to trial some of the proposed conservation works, so that our second round bid to the National Lottery has the best possible chance of success.”