The event will take place outside of the Harlequin Centre in Watford between 12pm and 4pm with members of Living the Dream School of Performing Arts taking part.
Proceeds from the flashmob will go towards Great Ormond Street Hospital in London.
Video: Living the Dream Company flash mob preview (YouTube)
In the past the Living the Dream Company performed a planned flashmob at St Pancras International.
The Living the Dream Performing Arts Company is a performing arts company based in Saint Albans for young people under the direction of Zoe Jackson.
The Living the Dream Summer Showcase will take place on on 13 and 14 August at at the Radlett Centre.