The unnamed victim is the state's first confirmed human fatality who had tested positive for the disease, and the first virus-related death in the country this year.
He was an 82-year-old Little Falls resident who was admitted to The Mountainside Hospital in Montclair on September 6, three days after he became ill. He was pronounced dead on September 14.
State epidemiologist Eddy Bresnitz said the man had other illnesses, but that West Nile was the principle cause of his death.
Both Whitman and state Health and Senior Services Commissioner Christine Grant said people should continue to take commonsense precautions still such as wearing long sleeves at night and using insect repellant.
"People shouldn't panic," Whitman said.
"Federal, state and local officials have been working tirelessly to detect West Nile virus, target mosquito control activities and promote prevention measures," the governor said in a statement.
The only human cases previously confirmed in New Jersey were a 72-year-old Bayonne woman, a 43-year-old man from Jersey City and a 54-year-old man with homes in Cliffside Park and Brooklyn, NY.
The woman is recovering at home. Both men were hospitalized for treatment and were reported to be recovering.
These new cases are evidence that the virus is firmly established in New Jersey and in the Northeast, Health Department Commissioner Christine Grant said.
Test results are pending for 18 people in New Jersey who have shown symptoms associated with the disease. State officials said none of those people appears to be critically ill.
The West Nile virus is transmitted through the bite of a mosquito that has drawn blood from an infected bird. It was first identified in the Western Hemisphere in September 1999.
Seven deaths in New York were blamed on the virus last year. There have been 12 human cases in New York City this year, including eight in Staten Island, but no deaths.
According to figures released last week, 838 crows found in 16 counties and one cockatiel have tested positive for the virus in New Jersey this year out of 1,527 crows tested.
At least three horses have been euthanized after they were found with the disease.
All 21 counties in the state have increased mosquito-control efforts, state officials said. Many of those programs include spraying pesticides to kill the mosquitoes at various stages of development.
The head of the federal Centers for Disease Control, Dr. Jeffrey P. Koplan, visited Bergen County on Thursday to review the state's efforts, calling them "a textbook example" of how to deal with a public health threat.
CDC spokesman Tom Skinner said additional human cases this year are becoming less likely.
"It's getting late in the season, so certainly as the weather becomes cool ... that shold impact how active the mosquitoes are," he said.
Generally, the disease causes flu-like symptoms or no problems at all, but it can be dangerous to young children, the elderly and anyone with a weakened immune system.