The church and charity is to carry out a major revival of Strawberry Field, a children’s home it has owned and run since the 1930s but which closed in 2005.
Singer-songwriter and Beatles frontman John Lennon lived near Strawberry Field as a child and joined the children there for garden parties in the summers.
He was later inspired by the experience to write the classic song Strawberry Fields Forever.
From the 1970s onwards, an iconic disused entrance to the site and its gates became a mecca for Beatles fans from all over the world.
Now the site is to be redeveloped, with the creation of a training hub for young people with learning disabilities and an exhibition exploring the links between Lennon and Strawberry Field.
Weber, which won the project-based contract in a competitive pitch against four other agencies, has been selected to develop and deliver the creative communications strategy to raise awareness of the global fundraising campaign for the redevelopment.
Carol-Anne Latta, PR & communications manager for The Salvation Army in the UK and Ireland, told PRWeek the agency had been given a "tough brief" in which it would have to balance the vision and values of a 150-year-old church with making a connection with Beatles fans around the world.
But she said Weber had impressed the church with its energy and how it tackled the creative part of the brief.
She added: "The Salvation Army is trusted and respected across the world, so we sought an agency with a global outlook, which understands our movement and our role as a custodian of the Strawberry Field site, and shares our vision to help transform lives. Weber Shandwick Manchester ticks all of those boxes and we’re excited to bring our campaign plans to life."
The Salvation Army said it uses PR and comms agencies on a project-by-project basis, and last did so to promote its work following a 2016 BBC documentary with Paul O’Grady, called 'The Sally Army and Me'.
Amy Hopkinson, associate director at Weber Shandwick Manchester and account lead on the project, said: "Every aspect of The Salvation Army project at Strawberry Field inspires excitement, from the incredible work that will be done with young people with learning disabilities, to the long-lasting connections Strawberry Field has to John Lennon and his legacy."