Others involved in organising the statue will also attend the ceremony on July 1 in the Sunken Garden at Kensington Palace.
Harry has reportedly arrived in the UK from California and is likely to be quarantining at his Frogmore Cottage home near Windsor Castle.
According to reports, the unveiling was due to be a larger gathering with many of Diana’s friends invited to the ceremony.
But the Daily Mail claims the princess’s friends were left disappointed after Covid-19 restrictions meant it had to be scaled back, with a separate larger event likely to take place in September.
Diana’s sons commissioned the artwork in 2017 – the 20th anniversary year of her death – to celebrate the princess’s life and legacy with the creation of a permanent statue.
The unveiling has been delayed, with the Covid-19 pandemic playing a part in the ceremony now taking place 60 years after the princess was born.
William and Harry’s troubled relationship is well documented but their mother will be their focus next Thursday as they commemorate her life.
In a statement when the project was announced, the royal brothers said: “Our mother touched so many lives. We hope the statue will help all those who visit Kensington Palace to reflect on her life and her legacy.”
Among those attending will be Diana’s close family, members of the statue committee, sculptor Ian Rank-Broadley, who created the statue, and garden designer Pip Morrison.