The soldiers, aged between 16 and 18 years old, paraded at Uniacke barracks in the town's Army Foundation College.
It was watched by a crowd of 3,000 including family and friends.
Lieutenant Colonel Oz Lane, the commanding officer, said the soldiers were "the future of the British Army" and should be "proud of their achievements".
The parade is only exceeded in size by Trooping the Colour in London, the college said.
Junior soldiers work on their leadership and team skills as part of the college's leadership and initiative training package.
They undertake a number of training activities, physical and mental challenges including a 30-hour challenge patrol across the Yorkshire Dales.
The college opened in 1998 and trains more than 1,300 soldiers for the Army.
More than 600 junior soldiers have taken part in a graduation parade at an army college in Harrogate.