Prince Al Waleed bin Talal has invested US$300 million (Dh1.1bn) in Twitter, the microblogging site that rose to prominence in the region during the Arab Spring.
Twitter, which allows people to send 140-character messages, has more than 100 million users - but is yet to build a revenue stream on a par with that of Facebook or Google.
The site has been valued at about $8bn, which would give the prince, who ranked 26th on this year's Forbes list of the world's richest people, a stake of about 3.75 per cent in the company.
The Saudi Arabian billionaire made the investment jointly with his Kingdom Holding Company, according to a notice issued by the company.
"HRH Prince Al Waleed bin Talal bin Abdulaziz Al Saud, and Kingdom Holding Company, announced … a combined investment of $300m in Twitter," said a statement posted to the Saudi Arabian stock exchange. "This investment was the result of several months of negotiations."
Prince Al Waleed has boosted his share in media investments over the years. He controls Rotana, one of the biggest broadcasters in the region, which runs Rotana Cinema, the second most lucrative channel by advertising revenues.
The prince also has a 7 per cent stake in Rupert Murdoch's troubled News Corp empire, which has been rocked by allegations of illegal phone hacking perpetrated by some of its journalists.
Prince Al Waleed also plans to launch Alarab, an Arabic-language news station. The channel, due to go on the air next year, will be based in either Bahrain or Dubai.
Karim Sabbagh, a senior partner at the consultancy Booz & Company, said that the investment in Twitter marked a "good complement" to Prince Al Waleed's portfolio.
"They had already made a significant push over the last three years to digital media. His investment in Twitter is a step in this direction," Mr Sabbagh said. "This is another way to reach out to his audience across multiple channels. It puts him in a very nice position."
It has also emerged that Twitter plans an initial public offering in the next two years.
Ahmed Halawani, the executive director of private equity at Kingdom Holding, told the television channel Al Arabiya that it could plan a share sale in two years. Kingdom Holding will not have voting rights or be represented on the Twitter board, the executive reportedly told Al Arabiya.
Despite that, Mr Sabbagh said that Prince Al Waleed's stake in Twitter was significant.