Cochrane set a new Pan Am record by winning in a time of 15 minutes 6.40 seconds.
Andrew Gemmell of U.S was second in 15:90.92 and Brandonn Almeida of Brazil was third in 15:11.70.
It's the second gold of the Games for Victoria native Cochrane, who won the men's 400 freestyle on Friday.
Canada ended up with four medals in the pool Saturday.
The women's 4x100 medley relay team took silver, while Sydney Pickrem earned a bronze medal in the women's 200 individual medley and the men's 4x100 relay added another bronze.