The events, or "tweet-ups'" will be held on February 12 and will raise money to support charity: water, a not-for-profit agency aimed at bringing clean drinking water to people in developing nations.
The individual Twestivals are being organised by volunteers and 100% of the proceeds will be directed towards the charity.
There are over 100 cities officially signed for the event across Europe, the Americas, Asia Pacific and the Middle East.
In London, where the first Twestival was held in 2008, the first 350 tickets sold out in just over an hour. An additional 150 tickets will be released Friday (January 23) at noon for the event which is being held in East London's Shoreditch studios.
The London Twestival Twitter page has over 400 followers and separate spill-over events are being planned for those unable to get a ticket.
Amanda Rose, Twestival organiser, said "We're already blown away by the global reception and how keen people are to invest their time and energy for free, to the Twestival and get behind charity: water.
"Social tweet ups like this are a great way to meet the faces behind those avatars while raising a lot of money for a fantastic cause.
"Twestival is organized 100% by volunteers and 100% of all event proceeds will go directly to support charity: water projects in developing countries, which will positively impact the lives of thousands."