The Venezuela Violence Monitor (OVV) said that 19,336 people had been murdered in 2011, an average of 53 per day in a country of 29 million.
"We must inform the nation that 2011 will end as the most violent year in the nation's history," the group said in a press release.
The group's figures indicate that the rate of homicides climbed to 67 per 100,000 inhabitants in 2011, constituting an "epidemic" of violence.
Violent crime is a leading concern, both for Venezuelans fearful for their personal safety and for left-wing President Hugo Chavez's government, which provides only limited violent crime figures.
In February, the interior minister admitted that the homicide rate had climbed to 48 murders per 100,000 inhabitants in 2010 but did not give a precise count, saying only that there were around 14,000 killings that year.
Venezuela's murder rates in 2010 and 2011 are the highest in South America, according to government data.
Venezuela's murder rate surpassed those of neighboring Colombia, which was 32 per 100,000 inhabitants last year, and Mexico, which was 14 per 100,000 inhabitants.
Colombia is beset by a leftist insurgency and Mexico is in the throes of a bloody war among drug cartels.
Several Latin American nations have murder rates multiple times higher than the global average.
The small Central American nation of Honduras is likely to have the highest murder rate in the world in 2011, with an estimated 86 per 100,000 inhabitants, the Violence Observatory in Tegucigalpa, a UN-backed monitor, reported in November.
