The ceremony will take place almost two decades to the day since the parliament officially assumed its legal powers.
The Queen, who will be accompanied by Prince Charles, the Duke of Rothesay, will formally address MSPs in the Parliament’s Debating Chamber.
The ceremony will also feature performances celebrating the best of Scottish music and culture.
Young people who were born on the day the devolved parliament was convened on 1 July 1999 – will also join the events.
The so-called “1 July babies” were an integral part of the 10th anniversary celebrations in 2009.
The parliament was reconvened two years after Scotland voted overwhelmingly for devolution in a referendum in 1997.
It initially sat at the General Assembly in Edinburgh before moving to its £431m purpose-built home at Holyrood in 2004.
The Queen was last in the landmark building in July 2016, marking the opening of the fifth session of the parliament.
During the parliament’s initial opening ceremony a specially-commissioned mace was unveiled in public for the first time – a gift from the Queen recognising the parliament’s authority.
It will form part of the 20th anniversary celebrations.
The Mace and the Crown of Scotland will be carried into the debating chamber ahead of the Queen’s address to MSPs.
Her address will be followed by speeches from the party leaders, including First Minister Nicola Sturgeon.
She is the sixth person to hold the office since 1999. The first person to become first minister was Donald Dewar, who died after less than two years in the post.
Following the ceremonial proceedings in the debating chamber, the Queen and Prince Charles will attend a reception in the main hall.