Medvedev visiting a cathedral Tuesday in Porvoo with his wife, Finnish President Tarja Halonen and her husband.
Medvedev, who often plays up his Internet savvy, told reporters in Finland that the project would boost his interaction with the online community.
"Thanks to LiveJournal, I will be able to make closer contact with Internet users," Medvedev said, according to a transcript on the Kremlin's web site.
As of Tuesday, the discussion board, located at Community.livejournal.com/blog_medvedev, contained videos and press materials from the Kremlin web site, where Medvedev last year opened a blog carrying video addresses to Internet users.
Medvedev will post a video on the blog Wednesday in which he "will talk about the development of the Internet and what the government should do to develop it," his spokeswoman, Natalya Timakova, told Interfax.
With virtually no criticism of the government on state-controlled television, the Russian blogosphere, and in particular LiveJournal, has become perhaps the country's most vibrant forum for political debate.
Many well-known politicians maintain LiveJournal blogs, including Kremlin critic Boris Nemtsov, wealthy businessman Alexander Lebedev, Kirov Governor Nikita Belykh and Federation Council Speaker Sergei Mironov.
Medvedev said he had not yet decided on a nickname for the blog, and LiveJournal users were already making suggestions on Medvedev's page on Tuesday afternoon.
One user suggested he use "preved_medved," or "hi, bear," a phrase from a racy cartoon that made the rounds of the Russian blogosphere in the run-up to Medvedev's election last year.
All comments posted on the blog will require approval from a moderator, according to the site. Comments containing swear words or offensive statements will not be posted, it said.
More than 30 comments had been posted on the blog as of Tuesday afternoon, some of which were critical of the president.
"How can you call for people (dissenters) to do something when you don't give anything in return (freedom)?" asked one user named "iceaxe."
Medvedev on Tuesday wrapped up a two-day visit to Finland by laying a wreath at the grave of Field Marshal C.G. Mannerheim, who led Finnish forces against the Red Army during World War II, and a trip to the town of Porvoo, where Tsar Alexander I declared Finland part of Russia.