The GB quartet of Laura Trott, Joanna Rowsell-Shand, Elinor Barker and Katie Archibald recorded a time of four minutes, 10.236 seconds to break their own record set during the heats.
Trott becomes the first British female athlete to win three gold medals, while Rowsell-Shand claims her second, with both riders having won the same event at London 2012.
Sarah Storey takes record 12th gold Paralympic medal
08/09/2016 AT 21:39
"It was phenomenal, the Americans did not produce a bad ride," six-time Olympic champion Sir Chris Hoy said on BBC Sport.
"It is so great to see the celebrations. So much work has gone into this and it is great to see the hard work paying off."
Laura Trott, Joanna Rowsell-Shand, Katie Archibald and Elinor Barker
Image credit: AFP
Earlier, Canada won the bronze-medal duel after overwhelming New Zealand by just under four seconds.
GB cycling boss defends gold-medal haul as questions are asked
17/08/2016 AT 12:55
Kenny wins crazy Keirin final to draw level with Hoy on record six golds
16/08/2016 AT 20:03