Contractors Spencer Group have begun setting up a works compound on the Horncliffe side of the bridge this week.
Work on the actual bridge, which celebrated its 200th anniversary last month, is due to start in October and take around 18 months.
It is another significant step for the structure which provides a key transport link and received £3.14m from The National Lottery Heritage Fund in September 2019.
The ambitious funding bid was put together by Northumberland County Council, Scottish Borders Council, Museums Northumberland and community group Friends of the Union Chain Bridge, following serious concerns about the condition of the world-famous structure.
Both councils have committed match funding totalling £5.7m towards the £10.5m scheme, with other fundraising activities continuing to be progressed by the Friends of Union Chain Bridge in support of the project.
Earlier this month Historic England confirmed a £250,000 grant towards the scheme.
As well as conserving the historic structure, the project team has also developed interpretation proposals and a comprehensive programme of community engagement and education activities.
David Renwick, director, England, North, The National Lottery Heritage Fund, said: “We are delighted to see that the work to ensure the iconic Union Chain Bridge is progressing and that through a programme of ambitious activities, our funding will provide exciting opportunities for people to explore the heritage and stories of this wonderful structure.”
Cllr Glen Sanderson from Northumberland County Council said: “This is yet another milestone, with work starting in earnest preparing for the main bridge works.
“We’re delighted to have got to this point with compounds being set up as there’s been so much work on both sides of the border to get us to this point.”
Built in 1820 by Captain Samuel Brown, the Union Chain Bridge is the oldest operational chain suspension bridge in the world still carrying vehicles.
The project team would love to hear from anyone who’s got a story to share about the bridge.