The Glade of Light memorial is a white marble “halo” bearing the names of those killed in the May 2017 outrage.
Families of those who lost loved ones have been able to make personalised memory capsules, containing mementos and messages, which are embedded inside the halo.
They have also been given the opportunity to visit privately before the memorial opens.
They were the youngest victim of the attack Saffie Roussos, eight, from Leyland, 18-year-old Georgina Callendar from Tarleton, Michelle Kiss from the Ribble Valley and Blackpool school receptionist Jane Tweddle.
The tribute is conceived as a living memorial – a peaceful garden space for remembrance and reflection, featuring plants which grow naturally in the UK countryside and have been selected to provide year-round colour and echo the changing seasons.
Around the anniversary every year, May 22, the white flowers of a hawthorn tree planted at its centre will bloom.
Manchester City Council leader Bev Craig said: “We will never forget those whose lives were lost on 22 May 2017.
“They already had a permanent place in the hearts of Manchester people. Now they have a lasting memorial in the heart of our city.
“The Glade of Light is a beautiful tribute to them and somewhere which will also have profound meaning for everyone affected by the attack.
“We hope the memorial site will be a place of peace and comfort, standing as a reminder that love is stronger than hate.”
Fences around the site, where work began in March last year, will be taken down for the public to be able to visit the memorial on Wednesday.
An official opening event is planned for spring 2022, ahead of the fifth anniversary of the attack.
The memorial is located between Manchester Cathedral and Chetham’s School of Music, at the foot of Fennel Street where it meets Victoria Street.
Hundreds of people were injured alongside the 22 who died, who included six children under 16.