Some 30 Britons were among 38 people killed by gunman Seifeddine Rezgui in the coastal resort of Port El Kantaoui on June 26 last year.
A one-minute silence will be observed in government buildings across the UK and in British embassies overseas on Monday at noon to pay respects to those who lost their lives and were affected by the attack.
The Minister for North Africa, Tobias Ellwood, will visit Tunisia for meetings with officials from the country’s government.
He will observe the silence in the UK Embassy in Tunis.
Speaking ahead of his visit, Mr Ellwood said: “As we mark the first anniversary of the horrific terrorist attack in Sousse we remember the 38 people brutally murdered, including 30 British nationals.
“A year on, we keep in our thoughts and prayers the family and friends who lost loved ones, those who were injured and others who witnessed this horrendous attack.
“We continue to work closely with Tunisia to enhance security and support economic development and reform. Tunisia will not stand alone in the face of the terrorist threat and the UK will be by its side.”
A special memorial service was held at Westminster Abbey in April for survivors and the victims’ friends and families.
Prince Harry laid a wreath at the Innocent Victims Memorial on behalf of his grandmother the Queen and delivered a reading during the service, which was conducted by the Dean of Westminster, the Very Reverend Dr John Hall, and attended by David Cameron.
Since the attack, the Foreign and Commonwealth Office has advised against all but essential travel to Tunisia.
The North African country’s tourism officials have called for the guidance to be relaxed because it suggests that the perpetrators are “on the winning side”.
Terror group Islamic State claimed responsibility for the attack.
The victims included Christopher Bell, 59, and his wife Sharon, 54, from Seacroft, Leeds.
Bruce Wilkinson, 72, of Goole, a retired worker from Drax power station near Selby, also died.