The Czech world No.2 on Sunday became the first player, man or woman, to win the event three times, Pliskova again serving without fear in a 6-4 4-6 7-5 tussle.
The two-hour, seven-minute triumph follows a near three-hour semi-final victory on Saturday night over Naomi Osaka and comes after Brisbane titles in 2017 and 2019.
Pliskova won a tight first set then jumped ahead with an early break in the second, before Keys launched a comeback similar to the one that propelled her into the decider on Saturday over another Czech Petra Kvitova.
But the second seed didn’t waver, again leaning on her serve and holding her own from the baseline.
A backhand error handed Pliskova a chance to serve out the match, but Keys broke back as the contest went beyond two hours.
History repeated in the following game though, Keys pushing a backhand long to gift the European another break she would not relinquish.
Pliskova is the first to make it three, the 27-year-old set to arrive for the Australian Open in good form as she chases a maiden major title from January 20.