The Pope was shown pressing a button on an iPad tablet.
The message read: "Dear friends, I am pleased to get in touch with you through Twitter. Thank you for your generous response. I bless all of you from my heart."
A spokesman said earlier the pontiff would "reach out to everyone" with accounts in eight languages.
The Pope's English account already has more than 660, 000 followers.
So far, the Pope's accounts @pontifex - which mean "pontiff" or "builder of bridges" - are only following each other.
Last year, the Pope sent his first tweet from a Vatican account to launch the Holy See's news information portal.
The leader of the world's 1.2 billion or so Roman Catholics is expected to sign off, rather than write, each individual tweet himself.
New platforms
The Pope's tweets are also expected to highlight messages from his weekly general audience, Sunday blessings and homilies on key Church holidays as well as papal reaction to world events.
The Vatican has long shown interest in using the latest communications technologies to spread the faith with the inventor of radio, Guglielmo Marconi, setting up Vatican Radio in 1931.
The Catholic Church also already uses several social media platforms, including text messages and YouTube, to communicate with young people.
Papal aides say the pontiff himself still prefers to communicate in longhand rather than using a computer keyboard.
Pope Benedict's six-year papacy has been bedevilled by poor communications.
Embarrassing clarifications had to be issued over such thorny issues as his 2005 speech about Islam and violence, and his stance on condoms and HIV.
source: BBC
