Prince Alwaleed bin Talal and his holding company have gone in for a combined total of $300 million.
Twitter allows users to send short messages of up to 140 characters.
It was instrumental in connecting protesters and relaying on-the-ground developments during this year's Arab uprisings.
Alwaleed, a nephew of the Saudi king, ranks 26th on Forbes' list of the world's richest people. He has a history of investing in media and technology companies.
The Associated Press contributed to this report.
