The 10ft-high figure is modelled on Private Herbert Burden, of the Northumberland Fusiliers, who had lied about his age to join up and was executed for desertion, aged 17.
The memorial forms the centrepiece of a tribute at the National Memorial Arboretum in Alrewas, near Lichfield, Staffordshire.
A semi-circle of stakes around the statue follow the seating pattern of a Greek theatre to symbolise "tragedy".
They record the names of the 306 British and Commonwealth servicemen shot at dawn by firing squads during and just after WWI.
The Shot at Dawn memorial created by Birmingham artist Andy De Comyn was unveiled on Thursday.
The National Memorial Arboretum, dedicated to those who aided the war effort in conflicts throughout the world, was officially opened last month by its patron, the Duchess of Kent.
Court martials
Director David Childs said: "Over 80 years of medical, psychological, psychiatric and sociological advances gives us advantages denied those who sat on the court martial boards that passed sentence.
"The memorial asks us to recognise these deaths as another of the tragedies that warfare has brought about and invites us to work for a peaceful future for all young men today."
During the period between August 1914 and March 1920 more than 20,000 servicemen were convicted by court-martials of offences which carried the death sentence.
Only 3,000 of those men were ordered to be put to death and of those just over 10% were executed.
Relatives of the men branded cowards have waged a long campaign to clear their names.
Records of the original court-martials are sketchy, most only including a summary of the trials and running to a couple of pages.
Shell shocked
Medical science has moved on a long way since the 1920s and now post-traumatic stress disorder is believed to be a possible cause for the unusual behaviour of the servicemen during WWI.
The forces have not carried out the death penalty for more than 70 years, but it still technically applies to five offences relating to mutiny and helping the enemy.
John Hipkin, who has been campaigning for the memorial, told the BBC's One O'Clock News of the poignancy of the memorial.
"I can empathise with these boys and wonder how they felt in their last hours on earth waiting for dawn.
"A terrible sense of betrayal must have entered them."
He added: "Many of these men were psychological casualties.
"At the end of World War I, more than 60,000 soldiers were given war pensions for shell shock."
Mr De Comyn said the memorial could provide a focus for descendants to grieve.
"It is somewhere for relatives to come and grieve and also for people to come and reflect about the tragedy of the wars of the 20th century," he said.