Matthew Buie of Duntroon, Ont., Julien Bahain of Sherbrooke, Que., Will Dean of Kelowna, B.C., and Rob Gibson of Kingston, Ont. led the entire race and won with a time of five minutes 42.22 seconds.
Cuba won silver in 5:44.39 and Argentina won bronze in 5:47.14.
Canada now has a total of five golds and two bronze medals in rowing.
Earlier, Liz Fenje and Katherine Sauks were victorious in the women's lightweight double sculls at Royal Henley Island.
Fenje, from Victoria and Sauks, from Owen Sound, Ont., won with a time of six minutes 57.23 seconds.
Cuba took silver in 7:00.36 and the United States won bronze in 7:03.86.
Also, Carling Zeeman of Cambridge, Ont. won gold in the women's single sculls.
Zeeman was more than seven seconds ahead of the competition with a winning time of seven minutes 30.86 seconds.
Katherine McFetridge of the United States took silver in 7:38.21 and Soraya Jadue of Chile won bronze in 7:43.34.