World No.1 Sabalenka, who reached the final without dropping a set, won 73 per cent of her first-serve points and faced just two break points en route to victory in a rematch of the 2025 French Open final won by Gauff.
She became only the fifth woman to win the Indian Wells and Miami WTA 1000 titles back-to-back, a feat known as the 'Sunshine Double' given the tournaments' respective locations in California and Florida.
She also became the first player to win back-to-back Miami titles since Australian ace Ash Barty in 2019 and 2021. The 2020 edition was cancelled due to COVID-19.
Sabalenka raced out to a 2-0 lead but Gauff, from nearby Delray Beach and appearing in her first Miami final, got on the board with a love hold and then repelled three break points in her next service game to get to 3-2.
But Sabalenka did not lose focus and eventually went up a double break on the world number four before closing out a dominant opening on her serve.
There was very little to separate the two players in the middle set which remained on serve until Gauff broke Sabalenka for the only time in the match to force a third set.
Sabalenka broke Gauff to open the decider, held at love in two consecutive service games to go 5-3 up and then sealed the victory with her fourth break of the match when Gauff sent a backhand wide.
The Belarusian joins Iga Swiatek (2022), Victoria Azarenka (2016), Kim Clijsters (2005) and Steffi Graf (1994, 1996) as the only women to complete the 'Sunshine Double'.
The Belarusian also improved to 23-1 on the year, her only loss coming in the Australian Open final at the hands of Elena Rybakina, whom she went on to beat in the Indian Wells final and Miami semi-finals.
"You've pushed me to be a better player,'' Sabalenka told Gauff during the trophy ceremony, before adding about the crowd, "You always bring a full stadium.''
Sabalenka got engaged this month, and she told Sky Sports: "I haven't had a moment to really stop and look back and realise what just happened in the last month but I'm so proud of the work that we've done, the fight that I was able to bring on court, the level and everything."
