Over the past few days everyone at the school has been busy emptying boxes and preparing classrooms for the opening.
Teresa Verrecchia, Head Teacher of St Dominic's, said: "It's wonderful to return home to a fantastic new school building and once again be in the heart of our community here in Petersburn.
"It's been a challenging period but everyone has worked together so well to ensure our young people were given the best care and attention to ensure their learning and development continued unaffected.
"We are so grateful to everyone at St Margaret's for making us feel so welcome and for the ongoing support they provided us for more than three years. Our pupils, parents and staff have been wonderful too - I am so proud of what we've achieved together."
The new school includes a nursery, a large games hall with a stage and sound system and is fully accessible.
The school's 170 pupils were given Tuesday and Wednesday off to allow staff to complete the move from St Margaret's.
Mrs Verrecchia added: "Our fantastic new school and nursery really is a new beginning - after the fire we lost all our records and resources and many of our staff and pupils are new and have no memories of the old building.
"It looks absolutely wonderful - particularly the teaching areas - it's so fresh and welcoming and I know our children with thrive and grow in their new environment.
Eddie Robertson, Morrison Construction's Managing Director for Central Scotland, said: "It is fantastic that pupils and teachers have been enjoying the state-of-the-art educational facilities on the first day at their new school.
"We are proud to have delivered this project that will provide a lasting benefit to the community and has positively impacted on the local economy by supporting six apprenticeships starts, six apprenticeship completions, two graduates and creating nine new jobs during construction.''
The fire which destroyed the old St Dominic's broke out at the end of the school day on March 26, 2015.