Chavez urged Venezuelans to watch his newly created account - chavezcandanga - after midnight Tuesday, saying "that point is when I let loose."
His first tweet in Spanish popped up at 14 minutes after midnight: "Hey how's it going? I appeared like I said I would: at midnight. I'm off to Brazil. And very happy to work for Venezuela. We will be victorious!!"
The socialist leader had more than 18,000 followers even before posting a single tweet, and that increased to more than 46,000 by midday on Wednesday.
Chavez, who has recently seen his popularity slip amid a recession and soaring inflation, has often been outmaneuvered by opponents who are more active on the Web than his supporters.
A close aide to Chavez, Public Works Minister Diosdado Cabello, said Monday that Chavez's supporters plan to "take over by assault" social networking sites like Twitter and Facebook.
"The opposition thinks it owns the social networking sites. They think Twitter and Facebook belong to them," Cabello was quoted as saying by the state news agency.
"We're fighting and there are 7 million of us who will have Twitter," he said, referring to members of Chavez's party. He said Chavez's Twitter feed would carry messages "from our commander."
Chavez, who was first elected in 1998, has built his presidency around being a communicator in touch with Venezuelans. In addition to a Sunday radio and TV program that lasts up to seven hours, Chavez also makes near-daily speeches on television that often last three hours or more.
The name chosen for his Twitter account - chavezcandanga - roughly translates as "devil" in some Latin American countries, but in Venezuela it can be used as an adjective to describe a rabble-rouser.