The events in Glasgow, Mons in Belgium, and London, form a key part of the Government's centenary programme and span the whole day on August 4 - the 100th anniversary of the date war was declared.
At 10am a service at Glasgow Cathedral will reflect the Commonwealth contribution to the war, followed by a wreath-laying service at the Cenotaph in George Square.
The events will be attended by the Prince of Wales, and the cathedral service will be shown live in George Square.
At 7.30pm on August 4 the Duke and Duchess of Cambridge and Prince Harry will attend a commemorative event at the Commonwealth War Graves Commission St Symphorien Military Cemetery in Mons, Belgium.
The twilight event for around 500 guests has been organised in partnership with the Commonwealth War Graves Commission, and will be based around music, poetry and readings.
And at 10pm a candlelit vigil at Westminster Abbey, which will include the gradual extinguishing of candles, will be attended by the Duchess of Cornwall.
The final candle will be extinguished at 11pm - the exact time that Britain joined the First World War - and the vigil will end with the cathedral in darkness except for a single light on the grave of the unknown warrior. Anglican churches around the UK will also be participating, along with other faith groups, to complement the event in London.