Residents in the city's Spandau district alarmed emergency services around 6 pm on Sunday when they found the boy trembling and vomiting on the Schönwalder Straße sidewalk, police said.
He had a blood alcohol level of 0.2 percent, or 2 promille, and remains hospitalised in intensive care.
Initial investigation has revealed that the child drank alcohol at a playground with his nine-year-old brother after acquiring the beverages from other youths there.
According to a government study released in May 2008, there has recently been a sharp increase in youth drinking in Germany.
Some 26 percent of German children in the study reported binge drinking – consuming five or more drinks in a row – in 2007. That was up from the 20 percent who reported binge drinking in 2006.
The number of hospital visits due to alcohol overconsumption among Germans aged 10 to 20 has also more than doubled since 2000, according to the report. Some 19,500 German youth between 12 and 17-years-old were hospitalized after drinking.
Teens are legally allowed to drink beer and wine in Germany at 16, though hard alcohol is prohibited until they turn 18.