Britain's Queen to resume official engagements after illness
The 86-year-old monarch will be joined by Prince Philip at a service at Westminster Abbey, followed by a reception at Marlborough House, central London, Buckingham Palace said.
There will be further engagements in London on Wednesday and Thursday, it said.
A Buckingham Palace spokesperson said it was "business as usual" after the Queen was forced to suspend her engagements, including a trip to Rome this weekend, due to the stomach illness.
She was hospitalised overnight on Sunday for treatment of gastroenteritis and left the hospital on Monday. It was her first hospitalisation in 10 years.
In 2002, she was treated at the same hospital for a minor knee operation and had minor, non-cancerous lesions removed from her face.
Buckingham Palace said that she was taken in as "a precautionary measure" and was otherwise in "good health".
It is believed that although she had cancelled her public engagements, the UK's head of state had kept busy meeting her advisers and reading government-related documents.
Queen's next public appearance will be as head of the Commonwealth for the Observance, Britain's biggest multi-faith service, an event held every year on the second Monday in March and attended by a 2,000-strong congregation, including 1,000 school children, and representatives of the Commonwealth's 54 nations.
It will launch this year's Commonwealth theme of "Opportunity through Enterprise".
The Queen's recorded Commonwealth Day message will be relayed by video to the congregation, which will be followed by a reception at Marlborough House in central London.
There will be further engagements in London on Wednesday and Thursday, including a visit to Tech City in the city's East End to tour a number of companies and a service at the Guards' Chapel.